WorldWideScience

Sample records for superalloy lattice block

  1. Superalloy Lattice Block Structures

    Science.gov (United States)

    Nathal, M. V.; Whittenberger, J. D.; Hebsur, M. G.; Kantzos, P. T.; Krause, D. L.

    2004-01-01

    Initial investigations of investment cast superalloy lattice block suggest that this technology will yield a low cost approach to utilize the high temperature strength and environmental resistance of superalloys in lightweight, damage tolerant structural configurations. Work to date has demonstrated that relatively large superalloy lattice block panels can be successfully investment cast from both IN-718 and Mar-M247. These castings exhibited mechanical properties consistent with the strength of the same superalloys measured from more conventional castings. The lattice block structure also accommodates significant deformation without failure, and is defect tolerant in fatigue. The potential of lattice block structures opens new opportunities for the use of superalloys in future generations of aircraft applications that demand strength and environmental resistance at elevated temperatures along with low weight.

  2. Superalloy Lattice Block Developed for Use in Lightweight, High-Temperature Structures

    Science.gov (United States)

    Hebsur, Mohan G.; Whittenberger, J. Daniel; Krause, David L.

    2003-01-01

    Successful development of advanced gas turbine engines for aircraft will require lightweight, high-temperature components. Currently titanium-aluminum- (TiAl) based alloys are envisioned for such applications because of their lower density (4 g/cm3) in comparison to superalloys (8.5 g/cm3), which have been utilized for hot turbine engine parts for over 50 years. However, a recently developed concept (lattice block) by JAMCORP, Inc., of Willmington, Massachusetts, would allow lightweight, high-temperature structures to be directly fabricated from superalloys and, thus, take advantage of their well-known, characterized properties. In its simplest state, lattice block is composed of thin ligaments arranged in a three dimensional triangulated trusslike configuration that forms a structurally rigid panel. Because lattice block can be fabricated by casting, correctly sized hardware is produced with little or no machining; thus very low cost manufacturing is possible. Together, the NASA Glenn Research Center and JAMCORP have extended their lattice block methodology for lower melting materials, such as Al alloys, to demonstrate that investment casting of superalloy lattice block is possible. This effort required advances in lattice block pattern design and assembly, higher temperature mold materials and mold fabrication technology, and foundry practice suitable for superalloys (ref. 1). Lattice block panels have been cast from two different Ni-base superalloys: IN 718, which is the most commonly utilized superalloy and retains its strength up to 650 C; and MAR M247, which possesses excellent mechanical properties to at least 1100 C. In addition to the open-cell lattice block geometry, same-sized lattice block panels containing a thin (1-mm-thick) solid face on one side have also been cast from both superalloys. The elevated-temperature mechanical properties of the open cell and face-sheeted superalloy lattice block panels are currently being examined, and the

  3. Lattice parameter variations during aging in nickel-base superalloys

    Science.gov (United States)

    Nathal, M. V.; Mackay, R. A.; Garlick, R. G.

    1988-01-01

    The importance of the state of coherency on measurements of gamma/gamma-prime lattice mismatch has been experimentally demonstrated during aging at 1000 C of specimens of an alloy with composition Ni-(8.6)Cr-(5.3)Al-(10.1)Co-(11.7)W-(1.2)Ti-(0.7)Mo (wt pct). Lattice parameter measurements are given as a function of aging time, and the corresponding sample microstructures are presented. The results show that changes of the two phases during aging did not influence the lattice parameter measurements, indicating that aging specimens to produce a semicoherent gamma/gamma-prime structure provides a good approximation of the true, unconstrained lattice mismatch.

  4. Temperature dependence of gamma-gamma prime lattice mismatch in nickel-base superalloys

    Science.gov (United States)

    Nathal, M. V.; Mackay, R. A.; Garlick, R. G.

    1985-01-01

    High temperature X-ray diffraction techniques were used to determine the gamma-gamma prime lattice mismatch of three different nickel-base superalloys at temperatures between 18 and 1000 C. The measurements were performed on oriented single-crystal disks which had been aged to produce a semicoherent gamma-gamma prime structure. The thermal expansion of the lattice parameters of the gamma and gamma-prime phases was described by a second-order polynomial expression. The expansion of the gamma-prime phase was consistently smaller than that of the gamma phase, which caused the lattice mismatch to become more negative at higher temperatures. It was also shown that high values of lattice mismatch resulted in increased rates of directional gamma-prime coarsening during elevated temperature creep exposure.

  5. Phase transformation and segregation to lattice defects in Ni-base superalloys.

    Science.gov (United States)

    Blavette, Didier; Cadel, Emmanuel; Pareige, Cristelle; Deconihout, Bernard; Caron, Pierre

    2007-12-01

    Nanostructural features of nickel-base superalloys as revealed by atom probe field ion microscopy (APFIM) and atom probe tomography (APT) are reviewed. The more salient information provided by these techniques is discussed through an almost exhaustive analysis of literature over the last 30 years. Atom probe techniques are shown to be able to measure the composition of tiny gamma' precipitates, a few nanometers in size, and to reveal chemical order within these precipitates. Phase separation kinetics in model NiCrAl alloys was investigated with both 3DAP and Monte-Carlo simulation. Results are shown to be in good agreement. Plane by plane analysis of {001} planes of Ni(3)Al-type gamma' phase makes it possible to estimate the degree of order as well as the preferential sites of various addition elements (Ti, Cr, Co, W, Ta, Re, Ru, etc.) included in superalloys. Clustering effects of Re in the gamma solid solution were also exhibited. Due to its ultrahigh depth resolution, the microchemistry of interfaces and grain boundaries can be characterized on an atomic scale. Grain boundaries in Astroloy or N18 superalloys were found to be enriched in B, Mo, and Cr and Al depleted.

  6. Block Separating Congruence Lattices of E-bisimple Semigroups

    Institute of Scientific and Technical Information of China (English)

    汪立民; 张静

    2004-01-01

    @@ In 1966, Reilly[1] Characterized bisimple w-scmigroups as Bruck-Reilly extensions of Groups.Later, Munn and Reilly[2] proved that a congruence on a bisimple w-semigroup is a group congruence or is idempotent-separating. Many author investigated the congruences on Bruck-Reilly extensions of some semigroups for about twenty years. In this paper, we study the block-separating congruence lattices of E-bisimple semigroups.

  7. Measurements of γ/γ' Lattice Misfit and γ' Volume Fraction for a Ru-containing Nickel-based Single Crystal Superalloy

    Institute of Scientific and Technical Information of China (English)

    X.P. Tan; J.L. Liu; X P Song; T. Jin; X.F. Sun; Z.Q. Hu

    2011-01-01

    A conventional X-ray difFractometer has been used to determine the -y/y' lattice misfit and γ' volume fraction for a Ru-containing nickel-based single crystal superalloy at room temperature. The rocking curve was used to characterize the distribution of subgrains. The diffraction peaks obtained by w-20 scan were used to determine the γ/γ' lattice misfit and γ' volume fraction. A three peaks fitting model was proposed. The peak fitting results are in good agreement with the model. The X-ray diffraction results indicate that the nickel-based single crystal superalloy was not a perfect monocrystalline material, which is comprised of many subgrains; and each subgrain also consists of large numbers of mosaic structures. In addition, two anomalous reflection phenomena were found during the experiment and discussed with respect to their occurrence and impact on the measurement. The experimental results show that the γ/γ' lattice misfit and ~/r volume fraction will be various at the different regions of its dendritic microstructure. The average γ/γ' lattice misfit and γ' volume fraction of the experimental alloy are approximately-0.2% and 70%, respectively. Furthermore, the γ' volume fraction calculated by atom microprobe (AP) data is also basically consistent with the experimental results.

  8. The discrete Lamb problem: Elastic lattice waves in a block medium

    CERN Document Server

    Aleksandrova, Nadezhda

    2014-01-01

    We study the propagation of transient waves under the action of a vertical step point load on the surface of a half-space filled by a block medium. The block medium is modeled by a square lattice of masses connected by springs in the directions of the axes x, y, and in the diagonal directions. The problem is solved by two methods. Analytically, we obtain asymptotic solutions in the vicinity of the Rayleigh wave at large time intervals. Numerically, we obtain a solution for any finite time interval. We compare these solutions with each other and with the solution to the Lamb problem for an elastic medium.

  9. Shape Optimization of Hollow Concrete Blocks Using the Lattice Discrete Particle Model

    Directory of Open Access Journals (Sweden)

    Fatemeh Javidan

    2013-01-01

    Full Text Available Hollow concrete blocks are one of the widely used building elements of masonry structures in whichthey are normally loaded under combined action of shear and compression. Accordingly and due to theirstructural importance, the present study intends to numerically search for an optimum shape of such blocks.The optimality index is selected to be the ratio of block’s failure strength to its weight, a non-dimensionalparameter, which needs to be maximized. The nonlinear analysis has been done using a homemade code writtenbased on the recently developed Lattice Discrete Particle Model (LDPM for the meso-scale simulation ofconcrete. This numerical approach accounts for the different aspects of concrete’s complex behavior such astensile fracturing, cohesive and frictional shearing and also its nonlinear compressive response. The modelparameters were calibrated against previously reported experimental data. Various two-core configurations forthe hollow blocks are examined, compared and discussed.

  10. Block renormalization group in a formalism with lattice wavelets: Correlation function formulas for interacting fermions

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, E. [Departamento Fisica-ICEx, UFMG, CP 702, Belo Horizonte MG 30.161-970 (Brazil); Procacci, A. [Departamento Matematica-ICEx, UFMG, CP 702, Belo Horizonte MG 30.161-970 (Brazil)

    1997-03-01

    Searching for a general and technically simple multiscale formalism to treat interacting fermions, we develop a (Wilson{endash}Kadanoff) block renormalization group mechanism, which, due to the property of {open_quotes}orthogonality between scales,{close_quotes} establishes a trivial link between the correlation functions and the effective potential flow, leading to simple expressions for the generating and correlation functions. Everything is based on the existence of {open_quotes}special configurations{close_quotes} (lattice wavelets) for multiscale problems: using a simple linear change of variables relating the initial fields to these configurations, we establish the formalism. The algebraic formulas show a perfect parallel with those obtained for bosonic problems, considered in previous works. {copyright} 1997 Academic Press, Inc.

  11. Finite-difference lattice Boltzmann method with a block-structured adaptive-mesh-refinement technique.

    Science.gov (United States)

    Fakhari, Abbas; Lee, Taehun

    2014-03-01

    An adaptive-mesh-refinement (AMR) algorithm for the finite-difference lattice Boltzmann method (FDLBM) is presented in this study. The idea behind the proposed AMR is to remove the need for a tree-type data structure. Instead, pointer attributes are used to determine the neighbors of a certain block via appropriate adjustment of its children identifications. As a result, the memory and time required for tree traversal are completely eliminated, leaving us with an efficient algorithm that is easier to implement and use on parallel machines. To allow different mesh sizes at separate parts of the computational domain, the Eulerian formulation of the streaming process is invoked. As a result, there is no need for rescaling the distribution functions or using a temporal interpolation at the fine-coarse grid boundaries. The accuracy and efficiency of the proposed FDLBM AMR are extensively assessed by investigating a variety of vorticity-dominated flow fields, including Taylor-Green vortex flow, lid-driven cavity flow, thin shear layer flow, and the flow past a square cylinder.

  12. Development of a Refractory High Entropy Superalloy

    Directory of Open Access Journals (Sweden)

    Oleg N. Senkov

    2016-03-01

    Full Text Available Microstructure, phase composition and mechanical properties of a refractory high entropy superalloy, AlMo0.5NbTa0.5TiZr, are reported in this work. The alloy consists of a nano-scale mixture of two phases produced by the decomposition from a high temperature body-centered cubic (BCC phase. The first phase is present in the form of cuboidal-shaped nano-precipitates aligned in rows along <100>-type directions, has a disordered BCC crystal structure with the lattice parameter a1 = 326.9 ± 0.5 pm and is rich in Mo, Nb and Ta. The second phase is present in the form of channels between the cuboidal nano-precipitates, has an ordered B2 crystal structure with the lattice parameter a2 = 330.4 ± 0.5 pm and is rich in Al, Ti and Zr. Both phases are coherent and have the same crystallographic orientation within the former grains. The formation of this modulated nano-phase structure is discussed in the framework of nucleation-and-growth and spinodal decomposition mechanisms. The yield strength of this refractory high entropy superalloy is superior to the yield strength of Ni-based superalloys in the temperature range of 20 °C to 1200 °C.

  13. Misfit in Inconel-Type Superalloy

    Directory of Open Access Journals (Sweden)

    Pavel Strunz

    2013-01-01

    Full Text Available An important parameter for the characterization of microstructural changes in nickel base superalloys is the misfit - the relative difference between lattice parameters of γ matrix and γ′ precipitates. The misfit in IN738LC superalloy was examined at POLDI time-of-flight (TOF neutron diffractometer both at room temperature and in situ at elevated temperatures using a high-temperature furnace. A careful out-of-furnace measurement yielded the lattice parameters of both γ and γ′ phase at room temperature (aγ=3.58611(10 Å, aγ′=3.58857(17 Å as well as the misfit (equal to 6.9(6×10-4. The in situ measurement at elevated temperatures provided the temperature dependence of the lattice parameters of γ (up to 1120°C and γ′ (up to 1000°C. Using these data, the evolution of the misfit with temperature was calculated. The misfit decreases with increasing temperature until it reaches zero value at a temperature around 800°C. Above 800°C, it becomes negative.

  14. Solubility of block copolymer surfactants in compressed CO{sub 2} using a lattice fluid hydrogen-bonding model

    Energy Technology Data Exchange (ETDEWEB)

    Takishima, Shigeki; O`Neill, M.L.; Johnston, K.P. [Univ. of Texas, Austin, TX (United States). Dept. of Chemical Engineering

    1997-07-01

    Supercritical carbon dioxide (CO{sub 2}) is an environmentally benign alternative to organic solvents in chemical processing. The solubilities of the homopolymers poly(ethylene glycol), poly(ethylene glycol) dimethyl ether (PEGDME), and poly(propylene glycol) (PPG) in CO{sub 2} were correlated with a lattice fluid hydrogen-bonding (LFHB) model, which was then used to predict solubilities of Pluronic L (PEG-PPG-PEG) and Pluronic R (PPG-PEG-PPG) triblock copolymers. Simple averaging rules were developed to evaluate the physical properties of the copolymers without introducing any adjustable parameters. For a given average molecular weight, the predictions of the model were quite reasonable and in some cases perhaps more accurate than the data, due to the large polydispersity of the samples. The model predicts the effects of total molecular weight, PEG/PPG ratio, terminal functional groups, temperature, and density on solubility. The much higher solubility of PPG versus PEG is due primarily to steric hindrance from the methyl branch, which weakens segment-segment interactions, and to a lesser extent to the stronger hydrogen bond donor strength of a primary (in the case of PEG) versus a secondary (in the case of PPG) alcohol terminal group. Consequently, the predicted solubilities of Pluronic L surfactants, which have stronger hydrogen bond donors on the terminal groups, are not much smaller than those of Pluronic R surfactants for given molecular weights of the blocks.

  15. Advanced superalloy airfoils

    Energy Technology Data Exchange (ETDEWEB)

    Gell, M.; Duhl, D.N.; Gupta, D.K.; Sheffler, K.D.

    1987-07-01

    Single-crystal superalloy technology for gas-turbine blades has combined the design of alloys for exclusive use in single-crystal form with advancements in directional solidification, in order to manufacture single-crystal castings with complex internal cooling passages. To these improvements have been incorporated metallic and ceramic coatings that further extend high temperature capabilities. The directional solidification of single-crystal turbine alloys requires total control of the thermal environment, using large vacuum furnaces capable of casting up to 30 blades at a time. All modern coatings involve the enrichment of the superalloy surface with elements that promote the formation and retention of alumina, which precludes further oxidation. 15 references.

  16. Interfacial dislocation motion and interactions in single-crystal superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Liu, B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Raabe, D. [Max Planck Inst. fur Eisenforshung. Dusseldorf (Germany); Roters, F. [Max Planck Inst. fur Eisenforshung. Dusseldorf (Germany); Arsenlis, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-10-01

    The early stage of high-temperature low-stress creep in single-crystal superalloys is characterized by the rapid development of interfacial dislocation networks. Although interfacial motion and dynamic recovery of these dislocation networks have long been expected to control the subsequent creep behavior, direct observation and hence in-depth understanding of such processes has not been achieved. Incorporating recent developments of discrete dislocation dynamics models, we simulate interfacial dislocation motion in the channel structures of single-crystal superalloys, and investigate how interfacial dislocation motion and dynamic recovery are affected by interfacial dislocation interactions and lattice misfit. Different types of dislocation interactions are considered: self, collinear, coplanar, Lomer junction, glissile junction, and Hirth junction. The simulation results show that strong dynamic recovery occurs due to the short-range reactions of collinear annihilation and Lomer junction formation. The misfit stress is found to induce and accelerate dynamic recovery of interfacial dislocation networks involving self-interaction and Hirth junction formation, but slow down the steady interfacial motion of coplanar and glissile junction forming dislocation networks. The insights gained from these simulations on high-temperature low-stress creep of single-crystal superalloys are also discussed.

  17. Large Amplitude Oscillatory Shear of Block Copolymer Spheres on a Body-Centered Cubic Lattice: Are Micelles Like Metals?

    Energy Technology Data Exchange (ETDEWEB)

    Torija, Maria A.; Choi, Soo-Hyung; Lodge, Timothy P.; Bates, Frank S. (UMM)

    2013-03-07

    Small-angle X-ray diffraction experiments have uncovered a remarkable mechanism of grain alignment during plastic deformation of ordered sphere-forming diblock copolymer micelles when subjected to large amplitude dynamic shearing. A nearly monodisperse poly(styrene-b-ethylene-alt-propylene) (SEP) diblock copolymer with block molecular weights of 42,000 and 60,000 was mixed with squalane (C{sub 30}H{sub 62}), an EP selective solvent, at a concentration of 10 wt %. After high temperature annealing, the sample formed an ordered polydomain morphology containing glassy S cores at room temperature. SAXS powder patterns confirm body-centered cubic (BCC) symmetry and reveal the development of a complex array of two-dimensionally resolved Bragg reflections following the application, and cessation, of oscillatory shearing. These diffraction results are interpreted on the basis of the classic mechanism of crystalline slip, which accounts for plastic deformation of ductile materials such as metals. Four distinct slip systems are shown to be active in this work, suggesting a robust basis for deforming and mixing of soft ordered solids.

  18. Large amplitude oscillatory shear of block copolymer spheres on a body-centered cubic lattice: are micelles like metals?

    Science.gov (United States)

    Torija, Maria A; Choi, Soo-Hyung; Lodge, Timothy P; Bates, Frank S

    2011-05-19

    Small-angle X-ray diffraction experiments have uncovered a remarkable mechanism of grain alignment during plastic deformation of ordered sphere-forming diblock copolymer micelles when subjected to large amplitude dynamic shearing. A nearly monodisperse poly(styrene-b-ethylene-alt-propylene) (SEP) diblock copolymer with block molecular weights of 42,000 and 60,000 was mixed with squalane (C(30)H(62)), an EP selective solvent, at a concentration of 10 wt%. After high temperature annealing, the sample formed an ordered polydomain morphology containing glassy S cores at room temperature. SAXS powder patterns confirm body-centered cubic (BCC) symmetry and reveal the development of a complex array of two-dimensionally resolved Bragg reflections following the application, and cessation, of oscillatory shearing. These diffraction results are interpreted on the basis of the classic mechanism of crystalline slip, which accounts for plastic deformation of ductile materials such as metals. Four distinct slip systems are shown to be active in this work, suggesting a robust basis for deforming and mixing of soft ordered solids.

  19. Application of Rapidly Solidified Superalloys.

    Science.gov (United States)

    1977-11-01

    those described earlier. It was noted, however, that the conventional lype stlperalloys (as evidenced in MAR M2(W, AF2-1DA and MAR M247 alloys, the...Activation Energy For Matrix Creep in MAR MAX() Alloy....................... I I *v 7o- SUMMARY This program is being conducted for the purpose of applying...can be achieved in superalloy powder materials for optimization of mechanical properties above I., Tm. MAR M200 alloy powder, processed and reacted in

  20. SHI Changxu: China's Superalloy Hero

    Institute of Scientific and Technical Information of China (English)

    XIN Ling

    2011-01-01

    Prof.Shi Changxu (Chang-hsu Shih), laureate of the State Top Scientific and Technological Award for 2010, is regarded as a pioneer in the development of superalloys in China and a world-class master of materials science with excellent leadership and strategic insights.In the 1960s, he and his colleagues worked out the first generation air-cooled nickel-based superalloy turbine blades for domestic fighter aircrafts which greatly enhanced the aeroengines' performance.Via the effective control of trace elements, he developed the low segregation technology to reduce the segregation of superalloys, for which the International Union of Materials Research Societies honored him with the "Innovations in Real Materials Award" in 1998.He advocated and promoted the research and development of carbon fibers and magnesium alloys in China as well as the establishment of the Chinese Academy of Engineering.Today, 30 years after retirement, Prof.Shi still works every day in his office to read latest research results, write advisory proposals and meet young visitors to give them his best support.

  1. SUPERALLOYS: AN INTRODUCTION WITH THERMAL ANALYSIS ...

    African Journals Online (AJOL)

    2015-09-01

    Sep 1, 2015 ... another precipitation strengthened nickel base superalloy, has a very good strength at ... Keywords: Superalloys; Phase reactions; Differential Thermal Analysis; Latent heat of ... high-temperature strength and creep resistance. ... Borides, a relatively low density of boride particles formed when boron ...

  2. Crystallographic, Microstructural, and Mechanical Characterization of Dynamically Processed EP741NP Superalloy

    Science.gov (United States)

    Sharma, A. D.; Sharma, A. K.; Thakur, N.

    2016-08-01

    Considerable progress has been made for the solidification of metal powders with improved properties by using varieties of metallurgical methods. However, solidification of superalloy powders offers many difficulties under traditional processes. This article outlines an extensive program being undertaken to produce monoliths of superalloys with enhanced microstructural and mechanical properties. EP741NP superalloy has been subjected to explosive shock wave loading to obtain uniform and crack-free monoliths. An axisymmetric cylindrical configuration with a plastic explosive of high-detonation velocity has been used to consolidate the superalloy powder nearer to its theoretical density (~98 pct). By careful design of experiments, detonation velocity has been measured vis-à-vis compaction of metal powders in a single-shot experiment by employing instrumented detonics. The shock-processed specimens characterized for phase, lattice parameter, and structural variation by X-ray diffraction technique show intact crystalline structure. Results obtained from Williamson-Hall method indicate small micro-strain (2.8 × 10-3) and decreased crystallite size. Energy-dispersive spectroscopy suggests no segregation within the specimens. Scanning electron microscopy shows fracture-less and micro-cracks/void-free compacts of superalloy indicating satisfactory sub-structural strength. Indentation experiments with variable loads (1.96 N and 2.94 N) performed on the shock-processed specimen cut along transverse section show high order of Vicker's micro-hardness value up to 486 H v. The tensile and compressive strengths of the superalloy monoliths cut along the consolidation axes have been found to be 824 and 834 MPa, respectively.

  3. Spin qubits in antidot lattices

    DEFF Research Database (Denmark)

    Pedersen, Jesper Goor; Flindt, Christian; Mortensen, Niels Asger;

    2008-01-01

    and density of states for a periodic potential modulation, referred to as an antidot lattice, and find that localized states appear, when designed defects are introduced in the lattice. Such defect states may form the building blocks for quantum computing in a large antidot lattice, allowing for coherent...

  4. Electrodeposition on Superalloy Substrates: a Review

    Science.gov (United States)

    Allahyarzadeh, M. H.; Aliofkhazraei, M.; Rouhaghdam, A. Sabour

    2016-02-01

    The present paper reviews various types of coatings, including platinum, platinum alloys, palladium, ruthenium, iridium, nickel, nickel alloys and composite coatings, on superalloy substrates using electrodeposition method. Attempts were carried out to represent an overall view of plating conditions and electrolyte and highlight the importance of the layer regarding to the performance of high-temperature coatings applied on superalloys, which is extensively used on gas-turbine components.

  5. Ni-based superalloys for turbine discs

    Science.gov (United States)

    Furrer, David; Fecht, Hans

    1999-01-01

    Superalloys have been developed for specific, specialized properties and applications. One of the main applications for nickel-based superalloys is gas-turbine-engine disc components for land-based power generation and aircraft propulsion. Turbine engines create harsh environments for materials due to the high operating temperatures and stress levels. Hence, as described in this article, many alloys used in the high-temperature turbine sections of these engines are very complex and highly optimized.

  6. Effect of boron addition on the microstructure and stress-rupture properties of directionally solidified superalloys

    Institute of Scientific and Technical Information of China (English)

    Bao-ping Wu; Lin-han Li; Jian-tao Wu; Zhen Wang; Yan-bin Wang; Xing-fu Chen; Jian-xin Dong; Jun-tao Li

    2014-01-01

    This study is focused on the effect of boron addition, in the range of 0.0007wt% to 0.03wt%, on the microstructure and stress-rupture properties of a directionally solidified superalloy. With increasing boron content in the as-cast alloys, there is an increase in the fraction of theγ′/γ eutectic and block borides precipitate around theγ′/γ eutectic. At a high boron content of 0.03wt%, there is precipitation of lamellar borides. Upon heat treatment, fine block borides tend to precipitate at grain boundaries with increasing boron content. Overall, the rupture life of the directionally solidified superalloy is significantly improved with the addition of nominal content of boron. However, the rupture life decreases when the boron content exceeds 0.03wt%.

  7. Microstructure-property relationships in directionally solidified single-crystal nickel-base superalloys

    Science.gov (United States)

    Mackay, Rebecca A.; Nathal, Michael V.

    1988-01-01

    This paper discusses some of the microstructural features which influence the creep properties of directionally solidified and single-crystal nickel-base superalloys. Gamma prime precipitate size and morphology, gamma-gamma (prime) lattice mismatch, phase instability, alloy composition, and processing variations are among the factors considered. Recent experimental results are reviewed and related to the operative deformation mechanisms and to the corresponding mechanical properties. Special emphasis is placed on the creep behavior of single-crystal superalloys at high temperatures, where directional gamma (prime) coarsening is prominent, and at lower temperatures, where gamma (prime) coarsening rates are significantly reduced. It can be seen that very subtle changes in microstructural features can have profound effects on the subsequent properties of these materials.

  8. Grain Boundary Engineering the Mechanical Properties of Allvac 718Plus(Trademark) Superalloy

    Science.gov (United States)

    Gabb, Timothy P.; Telesman, Jack; Garg, Anita; Lin, Peter; Provenzano, virgil; Heard, Robert; Miller, Herbert M.

    2010-01-01

    Grain Boundary Engineering can enhance the population of structurally-ordered "low S" Coincidence Site Lattice (CSL) grain boundaries in the microstructure. In some alloys, these "special" grain boundaries have been reported to improve overall resistance to corrosion, oxidation, and creep resistance. Such improvements could be quite beneficial for superalloys, especially in conditions which encourage damage and cracking at grain boundaries. Therefore, the effects of GBE processing on high-temperature mechanical properties of the cast and wrought superalloy Allvac 718Plus (Allvac ATI) were screened. Bar sections were subjected to varied GBE processing, and then consistently heat treated, machined, and tested at 650 C. Creep, tensile stress relaxation, and dwell fatigue crack growth tests were performed. The influences of GBE processing on microstructure, mechanical properties, and associated failure modes are discussed.

  9. Computer Aided Design of Ni-Based Single Crystal Superalloy for Industrial Gas Turbine Blades

    Science.gov (United States)

    Wei, Xianping; Gong, Xiufang; Yang, Gongxian; Wang, Haiwei; Li, Haisong; Chen, Xueda; Gao, Zhenhuan; Xu, Yongfeng; Yang, Ming

    The influence of molybdenum, tungsten and cobalt on stress-rupture properties of single crystal superalloy PWA1483 has been investigated using the simulated calculation of JMatPro software which ha s been widely used to develop single crystal superalloy, and the effect of alloying element on the stability of strengthening phase has been revealed by using the Thermo-Calc software. Those properties calculation results showed that the increasing of alloy content could facilitate the precipitation of TCP phases and increase the lattice misfit between γ and γ' phase, and the effect of molybdenum, tantalum was the strongest and that of cobalt was the weakest. Then the chemical composition was optimized, and the selected compositions showed excellent microstructure stability and stress-rupture properties by the confirmation of d-electrons concept and software calculation.

  10. RESEARCH ON REFRACTORY SUPERALLOYS IN THE HTM 21 PROJECT

    Institute of Scientific and Technical Information of China (English)

    Y.F.Gu; Y.Yamabe-Mitarai; C.Huang; H.Harada

    2005-01-01

    It was proposed that a new class of alloys based on platinum group metals (PGMs) were called refractory superalloys.These refractory superalloys have an fcc and LI2 coherent two-phase structure (similar to that of Ni-based superalloys), high melting temperatures and good potential as structural materials used at temperatures up to 1800℃.Our recent results on the microstructure evolution, deformation and fracture behavior of some of these refracotry superalloys, especial Ir- and Rh-base refractory superalloys were reported.

  11. Compositional Effects on Nickel-Base Superalloy Single Crystal Microstructures

    Science.gov (United States)

    MacKay, Rebecca A.; Gabb, Timothy P.; Garg,Anita; Rogers, Richard B.; Nathal, Michael V.

    2012-01-01

    Fourteen nickel-base superalloy single crystals containing 0 to 5 wt% chromium (Cr), 0 to 11 wt% cobalt (Co), 6 to 12 wt% molybdenum (Mo), 0 to 4 wt% rhenium (Re), and fixed amounts of aluminum (Al) and tantalum (Ta) were examined to determine the effect of bulk composition on basic microstructural parameters, including gamma' solvus, gamma' volume fraction, volume fraction of topologically close-packed (TCP) phases, phase chemistries, and gamma - gamma'. lattice mismatch. Regression models were developed to describe the influence of bulk alloy composition on the microstructural parameters and were compared to predictions by a commercially available software tool that used computational thermodynamics. Co produced the largest change in gamma' solvus over the wide compositional range used in this study, and Mo produced the largest effect on the gamma lattice parameter and the gamma - gamma' lattice mismatch over its compositional range, although Re had a very potent influence on all microstructural parameters investigated. Changing the Cr, Co, Mo, and Re contents in the bulk alloy had a significant impact on their concentrations in the gamma matrix and, to a smaller extent, in the gamma' phase. The gamma phase chemistries exhibited strong temperature dependencies that were influenced by the gamma and gamma' volume fractions. A computational thermodynamic modeling tool significantly underpredicted gamma' solvus temperatures and grossly overpredicted the amount of TCP phase at 982 C. Furthermore, the predictions by the software tool for the gamma - gamma' lattice mismatch were typically of the wrong sign and magnitude, but predictions could be improved if TCP formation was suspended within the software program. However, the statistical regression models provided excellent estimations of the microstructural parameters based on bulk alloy composition, thereby demonstrating their usefulness.

  12. Modelling of current-voltage characteristics of infrared photo-detectors based on type – II InAs/GaSb super-lattice diodes with unipolar blocking layers

    Directory of Open Access Journals (Sweden)

    Vishnu Gopal

    2015-09-01

    Full Text Available It is shown that current-voltage characteristics of infrared photo-detectors based on type-II InAs/GaSb super-lattices with uni-polar blocking layers can be modelled similar to a junction diode with a finite series resistance on account of blocking barriers. As an example this paper presents the results of a study of current-voltage characteristics of a type II InAs/GaSb super-lattice diode with PbIbN architecture using a recently proposed [J. Appl. Phys. 116, 084502 (2014] method for modelling of illuminated photovoltaic detectors. The thermal diffusion, generation – recombination (g-r, and ohmic currents are found as principal components besides a component of photocurrent due to background illumination. The experimentally observed reverse bias diode current in excess of thermal current (diffusion + g-r, photo-current and ohmic shunt current is reported to be best described by an exponential function of the type, Iexcess = Ir0 + K1exp(K2 V, where Ir0, K1 and K2 are fitting parameters and V is the applied bias voltage. The present investigations suggest that the exponential growth of excess current with the applied bias voltage may be taking place along the localized regions in the diode. These localized regions are the shunt resistance paths on account of the surface leakage currents and/or defects and dislocations in the base of the diode.

  13. Molecular dynamics study of mosaic structure in the Ni-based single-crystal superalloy

    Institute of Scientific and Technical Information of China (English)

    Zhu Tao; Wang Chong-Yu

    2006-01-01

    The mosaic structure in a Ni-based single-crystal superalloy is simulated by molecular dynamics using a potential employed in a modified analytic embedded atom method. From the calculated results we find that a closed three dimensional misfit dislocation network, with index of {100} and the side length of the mesh 89.6(A), is formed around a cuboidal γ' precipitate. Comparing the simulation results of the different mosaic models, we find that the side length of the mesh only depends on the lattice parameters of the γ and γ' phases as well as the γ/γ' interface direction, but is independent of the size and number of the cuboidal γ' precipitate. The density of dislocations is inversely proportional to the size of the cuboidal γ' precipitate, i.e. the amount of the dislocation is proportional to the total area of the γ/γ' interface, which may be used to explain the relation between the amount of the fine γ' particles and the creep rupture life of the superalloy. In addition, the closed three-dimensional networks assembled with the misfit dislocations can play a significant role in improving the mechanical properties of superalloys.

  14. First principles calculations of the site substitution behavior in gamma prime phase in nickel based superalloys

    Science.gov (United States)

    Chaudhari, Mrunalkumar

    Nickel based superalloys have superior high temperature mechanical strength, corrosion and creep resistance in harsh environments and found applications in the hot sections as turbine blades and turbine discs in jet engines and gas generator turbines in the aerospace and energy industries. The efficiency of these turbine engines depends on the turbine inlet temperature, which is determined by the high temperature strength and behavior of these superalloys. The microstructure of nickel based superalloys usually contains coherently precipitated gamma prime (gamma') Ni3Al phase within the random solid solution of the gamma (gamma) matrix, with the gamma' phase being the strengthening phase of the superalloys. How the alloying elements partition into the gamma and gamma' phases and especially in the site occupancy behaviors in the strengthening gamma' phases play a critical role in their high temperature mechanical behaviors. The goal of this dissertation is to study the site substitution behavior of the major alloying elements including Cr, Co and Ti through first principles based calculations. Site substitution energies have been calculated using the anti-site formation, the standard defect formation formalism, and the vacancy formation based formalism. Elements such as Cr and Ti were found to show strong preference for Al sublattice, whereas Co was found to have a compositionally dependent site preference. In addition, the interaction energies between Cr-Cr, Co-Co, Ti-Ti and Cr-Co atoms have also been determined. Along with the charge transfer, chemical bonding and alloy chemistry associated with the substitutions has been investigated by examining the charge density distributions and electronic density of states to explain the chemical nature of the site substitution. Results show that Cr and Co atoms prefer to be close by on either Al sublattice or on a Ni-Al mixed lattice, suggesting a potential tendency of Cr and Co segregation in the gamma' phase.

  15. Chemical driving force for rafting in superalloys

    CSIR Research Space (South Africa)

    Nabarro, FRN

    1997-08-15

    Full Text Available The author provides a brief overview of the chemical driving forces for rafting in superalloys. Until recently, all theories of the driving force for rafting have considered the compositions of the two phases to be fixed, although accepting...

  16. SUPERALLOYS: AN INTRODUCTION WITH THERMAL ANALYSIS

    Directory of Open Access Journals (Sweden)

    S. S. Raza

    2015-09-01

    Full Text Available Nickel based superalloys are commonly used materials in the aero industry and more specifically in the hot section of aero engines. These nickel and nickel iron based superalloys are precipitation strengthened alloys with a face centered cubic gamma matrix. Alloy 718, Allvac 718Plus and Waspaloy have been of great interest in the present study. Alloy 718 is a precipitation strengthened nickel-iron based alloy having gamma double prime phase (Ni3Nb as a main strengthening phase up to 650 °C. Waspaloy, another precipitation strengthened nickel base superalloy, has a very good strength at temperatures up to ~750 °C whereas Allvac 718Plus is a newly developed nickel based precipitation strengthened superalloy which retains good mechanical properties at up to ~700 °C. These three alloys were investigated in terms of how their respective solidification process reveals upon cooling.Latent heat of soloidification has been estimated for all three alloys. Differential thermal analyses (DTA have been used to approach the task. It was seen that Waspaloy has the smallest solidification range whereas Allvac 718Plus has the largest solidification interval in comparison. 

  17. A New Polycrystalline Co-Ni Superalloy

    Science.gov (United States)

    Knop, M.; Mulvey, P.; Ismail, F.; Radecka, A.; Rahman, K. M.; Lindley, T. C.; Shollock, B. A.; Hardy, M. C.; Moody, M. P.; Martin, T. L.; Bagot, P. A. J.; Dye, D.

    2014-12-01

    In 2006, a new-ordered L12 phase, Co3(Al,W), was discovered that can form coherently in a face-centered cubic (fcc) A1 Co matrix. Since then, a community has developed that is attempting to take these alloys forward into practical applications in gas turbines. A new candidate polycrystalline Co-Ni γ/ γ' superalloy, V208C, is presented that has the nominal composition 36Co-35Ni-15Cr-10Al-3W-1Ta (at.%). The alloy was produced by conventional powder metallurgy superalloy methods. After forging, a γ' fraction of ~56% and a secondary γ' size of 88 nm were obtained, with a grain size of 2.5 μm. The solvus temperature was 1000°C. The density was found to be 8.52 g cm-3, which is similar to existing Ni alloys with this level of γ'. The alloy showed the flow stress anomaly and a yield strength of 920 MPa at room temperature and 820 MPa at 800°C, similar to that of Mar-M247. These values are significantly higher than those found for either conventional solution and carbide-strengthened Co alloys or the γ/ γ' Co superalloys presented in the literature thus far. The oxidation resistance, with a mass gain of 0.08 mg cm-2 in 100 h at 800°C, is also comparable with that of existing high-temperature Ni superalloys. These results suggest that Co-based and Co-Ni superalloys may hold some promise for the future in gas turbine applications.

  18. Lattice Bosons

    CERN Document Server

    Chakrabarti, J; Bagchi, B; Chakrabarti, Jayprokas; Basu, Asis; Bagchi, Bijon

    2000-01-01

    Fermions on the lattice have bosonic excitations generated from the underlying periodic background. These, the lattice bosons, arise near the empty band or when the bands are nearly full. They do not depend on the nature of the interactions and exist for any fermion-fermion coupling. We discuss these lattice boson solutions for the Dirac Hamiltonian.

  19. Analysis of gamma prime shape changes in a single crystal Ni-base superalloy

    Science.gov (United States)

    Gayda, J.; Mackay, R. A.

    1989-01-01

    The microstructural evolution of a commercial single crystal superalloy, NASAIR 100, is analyzed using the existing high-temperature lattice mismatch data and high-temperature moduli obtained from tests on single crystals of gamma and gamma prime. A multiparticle analysis of the microstructural evolution is performed using a novel microstructural lattice simulation technique, MCFET. Under a uniaxial stress, a regular array of gamma prime particles in the simulated microstructure is predicted to coalesce and form a plate morphology, with the broad faces of the plates and stress axis perpendicular in tension but parallel in compression. These results are consistent with changes in gamma prime shape observed in NASAIR 100 following creep testing at 1000 C.

  20. Development of Wrought Superalloy in China

    Directory of Open Access Journals (Sweden)

    DU Jinhui

    2016-06-01

    Full Text Available Wrought superalloy development in China was reviewed in recent ten years. The achievement of basic research and development of industrial manufacture technologies were systematically described from the aspects of new alloys, new technologies of hot deformation. New alloys include: new disc materials 718Plus, GH4720Li and GH4065 alloy, combustion chamber alloy GH3230, and GH4706 alloy for gas turbine engines. New technologies include: ERS-CDS new technology of easy segregation materials, multi upsetting-drawing for improving the microstructure uniformity of bars, slow cooling and multi-cycle thermomechanical treatment for increasing hot plasticity of hard-to-work alloys. Finally, the further development of wrought superalloys was prospected.

  1. Thermal fatigue behavior of K465 superalloy

    Institute of Scientific and Technical Information of China (English)

    YANG Jinxia; ZHENG Qi; SUN Xiaofeng; GUAN Hengrong; HU Zhuangqi

    2006-01-01

    The thermal fatigue behavior of K465 superalloy was investigated at the peak temperature of 1050℃. By scanning electron microscopy (SEM) and optical microscopy, the main crack length was observed and measured. The initiation sites of the tested alloys are different in as-cast (named as K465) and solution heat treatment (named as SK465) conditions.In K465 alloy, most thermal fatigue cracks nucleate at (Nb,W,Ti)C carbides. In SK465 alloy, thermal fatigue cracks initiate in interdendritic regions, MC-type carbides and some interfaces. Thermal fatigue cracks propagate in transdendritic mode,and M6C-type carbides could retard thermal fatigue crack growth for SK465 superalloy.

  2. High-temperature protective coatings on superalloys

    Institute of Scientific and Technical Information of China (English)

    刘培生; 梁开明; 周宏余

    2002-01-01

    Protective coatings are essential for superalloys to serve as blades of gas turb ines at high temperatures, and they primarily include aluminide coating, MCrAlY overlay coating, thermal barrier coating and microcrystalline coating. In this paper, all these high-temperature coatings are reviewed as well as their preparing techniques. Based on the most application and the main failure way, the importance is then presented for further deepgoing study on the high-temperature oxidation law of aluminide coatings.

  3. Recent breakthroughs in nickel base superalloys

    OpenAIRE

    Honnorat, Y.

    1993-01-01

    Meanwhile the considerable amount of results acquired since more than sixty years in the study of this class of materials, the pre-eminence of nickel base superalloys in the gas turbine engineering, which is a domain in constant evolution, drives the significant progresses accomplished along the five last years. The knowledge, each day more precisely known, of the working conditions of the parts, the continuous increase of the computer capacity and the progressive sophistication of the design...

  4. Development of Wrought Superalloy in China

    OpenAIRE

    DU Jinhui; ZHAO Guangpu; Deng, Qun; LÜ Xudong; ZHANG Beijiang

    2016-01-01

    Wrought superalloy development in China was reviewed in recent ten years. The achievement of basic research and development of industrial manufacture technologies were systematically described from the aspects of new alloys, new technologies of hot deformation. New alloys include: new disc materials 718Plus, GH4720Li and GH4065 alloy, combustion chamber alloy GH3230, and GH4706 alloy for gas turbine engines. New technologies include: ERS-CDS new technology of easy segregation materials, multi...

  5. Effects of helium impurities on superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Selle, J.E.

    1977-07-01

    A review of the literature on the effects of helium impurities on superalloys at elevated temperatures was undertaken. The actual effects of these impurities vary depending on the alloy, composition of the gas atmosphere, and temperature. In general, exposure in helium produces significant but not catastrophic changes in the structure and properties of the alloys. The effects of these treatments on the structure, creep, fatigue, and mechanical properties of the various alloys are reviewed and discussed. Suggestions for future work are presented.

  6. Barrier Coatings for Refractory Metals and Superalloys

    Energy Technology Data Exchange (ETDEWEB)

    SM Sabol; BT Randall; JD Edington; CJ Larkin; BJ Close

    2006-02-23

    In the closed working fluid loop of the proposed Prometheus space nuclear power plant (SNPP), there is the potential for reaction of core and plant structural materials with gas phase impurities and gas phase transport of interstitial elements between superalloy and refractory metal alloy components during service. Primary concerns are surface oxidation, interstitial embrittlement of refractory metals and decarburization of superalloys. In parallel with kinetic investigations, this letter evaluates the ability of potential coatings to prevent or impede communication between reactor and plant components. Key coating requirements are identified and current technology coating materials are reviewed relative to these requirements. Candidate coatings are identified for future evaluation based on current knowledge of design parameters and anticipated environment. Coatings were identified for superalloys and refractory metals to provide diffusion barriers to interstitial transport and act as reactive barriers to potential oxidation. Due to their high stability at low oxygen potential, alumina formers are most promising for oxidation protection given the anticipated coolant gas chemistry. A sublayer of iridium is recommended to provide inherent diffusion resistance to interstitials. Based on specific base metal selection, a thin film substrate--coating interdiffusion barrier layer may be necessary to meet mission life.

  7. Thermomechanical fatigue in single crystal superalloys

    Directory of Open Access Journals (Sweden)

    Moverare Johan J.

    2014-01-01

    Full Text Available Thermomechanical fatigue (TMF is a mechanism of deformation which is growing in importance due to the efficiency of modern cooling systems and the manner in which turbines and associated turbomachinery are now being operated. Unfortunately, at the present time, relatively little research has been carried out particularly on TMF of single crystal (SX superalloys, probably because the testing is significantly more challenging than the more standard creep and low cycle fatigue (LCF cases; the scarcity and relative expense of the material are additional factors. In this paper, the authors summarise their experiences on the TMF testing of SX superalloys, built up over several years. Emphasis is placed upon describing: (i the nature of the testing method, the challenges involved in ensuring that an given testing methodology is representative of engine conditions (ii the behaviour of a typical Re-containing second generation alloy such as CMSX-4, and its differing performance in out-of-phase/in-phase loading and crystallographic orientation and (iii the differences in behaviour displayed by the Re-containing alloys and new Re-free variants such as STAL15. It is demonstrated that the Re-containing superalloys are prone to different degradation mechanisms involving for example microtwinning, TCP precipitation and recrystallisation. The performance of STAL15 is not too inferior to alloys such as CMSX-4, suggesting that creep resistance itself does not correlate strongly with resistance to TMF. The implications for alloy design efforts are discussed.

  8. Effect of Zr addition on precipitates in K4169 superalloy

    National Research Council Canada - National Science Library

    Li Yamin Liu Hongjun Liu Jie Wang Zhipeng Hao Yuan

    2012-01-01

    In order to investigate the effect of Zr addition on the precipitations of K4169 superalloy, a manual electric arc furnace was used to prepare the superalloy with different Zr addition from 0.03wt.% to 0.07wt...

  9. 75 FR 67100 - Superalloy Degassed Chromium From Japan

    Science.gov (United States)

    2010-11-01

    ... COMMISSION Superalloy Degassed Chromium From Japan AGENCY: United States International Trade Commission... chromium from Japan. SUMMARY: The Commission hereby gives notice that it has instituted a review pursuant... revocation of the antidumping duty order on superalloy degassed chromium from Japan would be likely to lead...

  10. Superradiance Lattice

    CERN Document Server

    Wang, Da-Wei; Zhu, Shi-Yao; Scully, Marlan O

    2014-01-01

    We show that the timed Dicke states of a collection of three-level atoms can form a tight-binding lattice in the momentum space. This lattice, coined the superradiance lattice (SL), can be constructed based on an electromagnetically induced transparency (EIT) system. For a one-dimensional SL, we need the coupling field of the EIT system to be a standing wave. The detuning between the two components of the standing wave introduces an effective electric field. The quantum behaviours of electrons in lattices, such as Bloch oscillations, Wannier-Stark ladders, Bloch band collapsing and dynamic localization can be observed in the SL. The SL can be extended to two, three and even higher dimensions where no analogous real space lattices exist and new physics are waiting to be explored.

  11. Influence of composition on microstructural parameters of single crystal nickel-base superalloys

    Energy Technology Data Exchange (ETDEWEB)

    MacKay, R.A., E-mail: Rebecca.A.MacKay@nasa.gov [NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, Ohio 44135 (United States); Gabb, T.P. [NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, Ohio 44135 (United States); Garg, A. [NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, Ohio 44135 (United States); University of Toledo, 2801 W. Bancroft, Toledo, Ohio 43606 (United States); Rogers, R.B.; Nathal, M.V. [NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, Ohio 44135 (United States)

    2012-08-15

    Fourteen nickel-base superalloy single crystals containing a range of chromium (Cr), cobalt (Co), molybdenum (Mo), and rhenium (Re) levels, and fixed amounts of aluminum (Al) and tantalum (Ta), were examined to determine the effect of bulk composition on basic microstructural parameters, including {gamma} Prime solvus, {gamma} Prime volume fraction, topologically close-packed (TCP) phases, {gamma} and {gamma} Prime phase chemistries, and {gamma}-{gamma} Prime lattice mismatch. Regression models describing the influence of bulk alloy composition on each of the microstructural parameters were developed and compared to predictions by a commercially-available software tool that used computational thermodynamics. Co produced the largest change in {gamma} Prime solvus over the wide compositional range explored and Mo produced the biggest effect on the {gamma} lattice parameter over its range, although Re had a very potent influence on all microstructural parameters investigated. Changing the Cr, Co, Mo, and Re contents in the bulk alloy had an impact on their concentrations in the {gamma} matrix and to a smaller extent in the {gamma} Prime phase. The software tool under-predicted {gamma} Prime solvus temperatures and {gamma} Prime volume fractions, and over-predicted TCP phase volume fractions at 982 Degree-Sign C. However, the statistical regression models provided excellent estimations of the microstructural parameters and demonstrated the usefulness of such formulas. - Highlights: Black-Right-Pointing-Pointer Effects of Cr, Co, Mo, and Re on microstructure in new low density superalloys Black-Right-Pointing-Pointer Co produced a large change in {gamma} Prime solvus; Mo had a large effect on lattice mismatch. Black-Right-Pointing-Pointer Re exhibited very potent influence on all microstructural parameters was investigated. Black-Right-Pointing-Pointer {gamma} and {gamma} Prime phase chemistries both varied with temperature and alloy composition. Black

  12. Low-Cobalt Powder-Metallurgy Superalloy

    Science.gov (United States)

    Harf, F. H.

    1986-01-01

    Highly-stressed jet-engine parts made with less cobalt. Udimet 700* (or equivalent) is common nickel-based superalloy used in hot sections of jet engines for many years. This alloy, while normally used in wrought condition, also gas-atomized into prealloyed powder-metallurgy (PM) product. Product can be consolidated by hot isostatically pressing (HIPPM condition) and formed into parts such as turbine disk. Such jet-engine disks "see" both high stresses and temperatures to 1,400 degrees F (760 degrees C).

  13. Conditions Of Directional Solidification Affect Superalloy

    Science.gov (United States)

    Schmidt, D. D.; Alter, W. S.; Hamilton, W. D.; Parr, R. A.

    1992-01-01

    Report describes experiments to determine effects of gradient of temperature and rate of solidification on microstructure and fatigue properties of nickel-based superalloy MAR-M246(Hf). Enhancement of properties extends lifespans of objects, including turbo-pump blades of Space Shuttle Main Engines. Results indicate significant improvements in fatigue properties derived through manipulation of parameters of directional solidification. Particularly MAR-M246(Hf) for turbine blades contains small, well-dispersed blocky carbide and microstructure with small distances between dendrite arms, and without eutectic phase.

  14. Low Melt Height Solidification of Superalloys

    Science.gov (United States)

    Montakhab, Mehdi; Bacak, Mert; Balikci, Ercan

    2016-06-01

    Effect of a reduced melt height in the directional solidification of a superalloy has been investigated by two methods: vertical Bridgman (VB) and vertical Bridgman with a submerged baffle (VBSB). The latter is a relatively new technique and provides a reduced melt height ahead of the solidifying interface. A low melt height leads to a larger primary dendrite arm spacing but a lower mushy length, melt-back transition length, and porosity. The VBSB technique yields up to 38 pct reduction in the porosity. This may improve a component's mechanical strength especially in a creep-fatigue type dynamic loading.

  15. Stress rupture properties of GH4169 superalloy

    Directory of Open Access Journals (Sweden)

    Xudong Lu

    2014-04-01

    Full Text Available GH4169 alloy is a nickel-based superalloy extensively used in the aircraft engine industry because of its excellent mechanical properties and good fabrication ability. The mechanical properties of the GH4169 at high temperature, rupture stress under severe condition deserves a close attention. In this paper, the creep rupture of the GH4169 alloy under constant load and different temperatures from 550 °C to 700 °C conditions is systematically evaluated and major impact factors in the stress rupture behavior are analyzed. Furthermore, an improving method for the alloy stress rupture is proposed.

  16. A New Approach of Designing Superalloys for Low Density

    Science.gov (United States)

    MacKay, Rebecca A.; Gabb, Timothy P.; Smialek, James L.; Nathal, Michael V.

    2010-01-01

    New low-density single-crystal (LDS) alloy, have bee. developed for turbine blade applications, which have the potential for significant improvements in the thrust-to-weight ratio over current production superalloys. An innovative alloying strategy was wed to achieve alloy density reductions, high-temperature creep resistance, microstructural stability, and cyclic oxidation resistance. The alloy design relies on molybdenum as a potent. lower-density solid-solution strengthener in the nickel-based superalloy. Low alloy density was also achieved with modest rhenium levels tmd the absence of tungsten. Microstructural, physical mechanical, and environmental testing demonstrated the feasibility of this new LDS superalloy design.

  17. MICROMECHANICS OF THE DAMAGE-INDUCED CELLULAR MICROSTRUCTURE IN SINGLE CRYSTAL Ni-BASED SUPERALLOYS

    Institute of Scientific and Technical Information of China (English)

    M.Sakaguchi; M.Okazaki

    2004-01-01

    An analytical method to investigate the morphological evolution of the cellular microstructure is explored and proposed. The method is essentially based on the Eshelby's micromechanics theory, and it is extended so as to be applied for a material system containing inclusions with high volume fraction, by employing the average stress field approximation by Mori and Tanaka. The proposed method enables us to discuss a stable shape of precipitate in the material system, which must be influenced by many factors: e.g., volume fraction of precipitate; Young's modulus ratio and lattice misfit between matrix and precipitate; external stress field in multiaxial state; and heterogeneity of plastic strain between matrix and precipitate. A series of numerical calculations were summarized on stable shape maps. The application of the method to predict the γ' rafting in superalloys during creep showed that the heterogeneity of plastic strain between matrix and precipitates may play a significant role in the shape stability of the precipitate. Furthermore, it was shown that the method was successfully applied to estimate the morphology of the cellular microstructure formed in CMSX-4single crystal Ni-based superalloy.

  18. Modelling and simulation of superalloys. Book of abstracts

    Energy Technology Data Exchange (ETDEWEB)

    Rogal, Jutta; Hammerschmidt, Thomas; Drautz, Ralf (eds.)

    2014-07-01

    Superalloys are multi-component materials with complex microstructures that offer unique properties for high-temperature applications. The complexity of the superalloy materials makes it particularly challenging to obtain fundamental insight into their behaviour from the atomic structure to turbine blades. Recent advances in modelling and simulation of superalloys contribute to a better understanding and prediction of materials properties and therefore offer guidance for the development of new alloys. This workshop will give an overview of recent progress in modelling and simulation of materials for superalloys, with a focus on single crystal Ni-base and Co-base alloys. Topics will include electronic structure methods, atomistic simulations, microstructure modelling and modelling of microstructural evolution, solidification and process simulation as well as the modelling of phase stability and thermodynamics.

  19. Microstructure Evolution of a Single Crystal Nickel-Base Superalloy During Heat Treatment and Creep

    Institute of Scientific and Technical Information of China (English)

    YANG Da-yun,JIN Tao; ZHAO Nai-ren; WANG ZHi-hui; SUN Xiao-feng; GUAN Heng-rong; HU Zhuang-qi

    2004-01-01

    Microstructure evolution of a single crystal nickel-base superalloy during heat treatment and tensile creep at1010℃ and 248 MPa for 30h was observed and analyzed. Internal stresses because of lattice mismatch between γ and γphase provided the driving force for γ shape evolution during heat treatment. More than 65 vol. % distorted cubic γ phase keeping coherency with the γ matrix precipitated after solution at 1295 ℃ for 32h. The shape of γ phase was perfectly cubic with increasing precipitate size during the two-step aging treatment. Due to the applied stress and internal stress field the continuous γ-γ lamellar structure perpendicular to the applied stress was formed after 30h tensile creep.

  20. The development of directional coarsening of the gamma-prime precipitate in superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.; Ebert, L. J.

    1983-01-01

    A study has been made of the kinetics of the directional coarsening of the gamma-prime precipitates in Ni-5.8Al-14.6Mo-6.2Ta single crystals during creep at 982 C. In this alloy, which is characterized by a large negative lattice misfit between the gamma-prime precipitate and the gamma matrix, the formation of gamma-prime rafts begins during primary creep, and the rafts grow in length as the deformation proceeds into steady-state creep. After that, the length of the rafts stabilizes. The thickness of the rafts remains constant from primary up to tertiary creep. The directional coarsening behavior of the alloy studied is similar to that of a more conventional single-crystal superalloy having a substantially smaller negative misfit.

  1. Formation of Minor Phases in a Nickel-Based Disk Superalloy

    Science.gov (United States)

    Gabb, T. P.; Garg, A.; Miller, D. R.; Sudbrack, C. K.; Hull, D. R.; Johnson, D.; Rogers, R. B.; Gayda, J.; Semiatin, S. L.

    2012-01-01

    The minor phases of powder metallurgy disk superalloy LSHR were studied. Samples were consistently heat treated at three different temperatures for long times to approximate equilibrium. Additional heat treatments were also performed for shorter times, to then assess non-equilibrium conditions. Minor phases including MC carbides, M23C6 carbides, M3B2 borides, and sigma were identified. Their transformation temperatures, lattice parameters, compositions, average sizes and total area fractions were determined, and compared to estimates of an existing phase prediction software package. Parameters measured at equilibrium sometimes agreed reasonably well with software model estimates, with potential for further improvements. Results for shorter times representing non-equilibrium indicated significant potential for further extension of the software to such conditions, which are more commonly observed during heat treatments and service at high temperatures for disk applications.

  2. A new approach to develop complicated superalloy castings

    Institute of Scientific and Technical Information of China (English)

    WU Jian-tao; FENG Di; LI Jun-tao; KONG Sheng-guo; PEI Zhong-ye

    2006-01-01

    An integrative computer aided investment casting (CAIC) technology for making complicated superalloy castings was described. Key processes of CAIC were discussed including the choice of SLS (Selectively Laser Sinterihg)materials, sintering parameters, solidification simulation and gating and risering system optimization. Using CAIC process,many large-sized quality superalloy castings with complicated shape and thin wall have been produced successfully and economically in Central Iron & steel Research Institute (CISRI).

  3. A new approach to develop complicated superalloy castings

    Directory of Open Access Journals (Sweden)

    WU Jian-tao

    2006-05-01

    Full Text Available An integrative computer aided investment casting (CAIC technology for making complicated superalloy castings was described. Key processes of CAIC were discussed including the choice of SLS (Selectively Laser Sintering materials, sintering parameters, solidification simulation and gating and risering system optimization. Using CAIC process, many large-sized quality superalloy castings with complicated shape and thin wall have been produced successfully and economically in Central Iron & steel Research Institute (CISRI.

  4. Lattice theory

    CERN Document Server

    Donnellan, Thomas; Maxwell, E A; Plumpton, C

    1968-01-01

    Lattice Theory presents an elementary account of a significant branch of contemporary mathematics concerning lattice theory. This book discusses the unusual features, which include the presentation and exploitation of partitions of a finite set. Organized into six chapters, this book begins with an overview of the concept of several topics, including sets in general, the relations and operations, the relation of equivalence, and the relation of congruence. This text then defines the relation of partial order and then partially ordered sets, including chains. Other chapters examine the properti

  5. Hot deformation behavior of FGH96 superalloys

    Institute of Scientific and Technical Information of China (English)

    Jiantao Liu; Guoquan Liu; Benfu Hu; Yuepeng Song; Ziran Qin; Yiwen Zhang

    2006-01-01

    The hot deformation behavior of FGH96 superalloys at 1070-1170℃ and 5×10-4-2×10-1 s-1 were investigated by means of the isothermal compression tests at a Gleeble-1500 thermal mechanical simulator. The results show that dynamic recovery acts as the main softening mechanism below 2×10-3 s-1, whereas dynamic recrystallization acts as the main softening mechanism above 2×10-3 s-1during deformation; the temperature increase caused by the deformation and the corresponding softening stress is negligible; the thermal-mechanical constitutive model to describe the hot deformation behavior is given, and the value of the apparent deformation activation energy (Qdef) is determined to be 354.93 kJ/mol.

  6. Creep Behaviour of Modified Mar-247 Superalloy

    Directory of Open Access Journals (Sweden)

    Cieśla M.

    2016-06-01

    Full Text Available The paper presents the results of analysis of creep behaviour in short term creep tests of cast MAR-247 nickel-based superalloy samples made using various modification techniques and heat treatment. The accelerated creep tests were performed under temperature of 982 °C and the axial stresses of σ = 150 MPa (variant I and 200 MPa (variant II. The creep behaviour was analysed based on: creep durability (creep rupture life, steady-state creep rate and morphological parameters of macro- and microstructure. It was observed that the grain size determines the creep durability in case of test conditions used in variant I, durability of coarse-grained samples was significantly higher.

  7. Effects of Microstructural Parameters on Creep of Nickel-Base Superalloy Single Crystals

    Science.gov (United States)

    MacKay, Rebecca A.; Gabb, Timothy P.; Nathal, Michael V.

    2013-01-01

    Microstructure-sensitive creep models have been developed for Ni-base superalloy single crystals. Creep rupture testing was conducted on fourteen single crystal alloys at two applied stress levels at each of two temperatures, 982 and 1093 C. The variation in creep lives among the different alloys could be explained with regression models containing relatively few microstructural parameters. At 982 C, gamma-gamma prime lattice mismatch, gamma prime volume fraction, and initial gamma prime size were statistically significant in explaining the creep rupture lives. At 1093 C, only lattice mismatch and gamma prime volume fraction were significant. These models could explain from 84 to 94 percent of the variation in creep lives, depending on test condition. Longer creep lives were associated with alloys having more negative lattice mismatch, lower gamma prime volume fractions, and finer gamma prime sizes. The gamma-gamma prime lattice mismatch exhibited the strongest influence of all the microstructural parameters at both temperatures. Although a majority of the alloys in this study were stable with respect to topologically close packed (TCP) phases, it appeared that up to approximately 2 vol% TCP phase did not affect the 1093 C creep lives under applied stresses that produced lives of approximately 200 to 300 h. In contrast, TCP phase contents of approximately 2 vol% were detrimental at lower applied stresses where creep lives were longer. A regression model was also developed for the as-heat treated initial gamma prime size; this model showed that gamma prime solvus temperature, gamma-gamma prime lattice mismatch, and bulk Re content were all statistically significant.

  8. Effect of Ce+ Ion Implantation upon Oxidation Resistance of Superalloy K38G

    Institute of Scientific and Technical Information of China (English)

    Qian Yuhai; Li Meishuan; Duo Shuwang; Zhao Youming

    2005-01-01

    The oxidation behavior (isothermal and cyclic oxidation) of cast superalloy K38G and the effect of Ce+ ion implantation with dose of 1×1017 ions/cm2 upon its oxidation resistance at 900 and 1000 ℃ in air were investigated. Meanwhile, the influence of Ce+ implantation on oxidation behavior of K38G with pre-oxide scale at 1000 ℃ in air was compared. The pre-oxidation was performed at 1000 ℃ in static air for 0.25 and 1.5 h, respectively. It is shown that the homogeneous external mixture oxide of rutile TiO2+Cr2O3 and non-continuous internal oxide of Al2O3 are formed during the oxidation procedure in all the cases. The isothermal oxidation resistance and the cracking or spallation resistance of superalloy K38G implanted with Ce+ by both of the two different implantation ways are not improved notably. This may be attributed to the mixed oxide composition characteristics and the blocking effect differences of Ce+ segregation along the oxide grain boundaries on the transport process for different diffusing ions.

  9. Hot Corrosion of Coated Single Crystal Superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Simms, N. J.; Encinas-Oropesa, A.; Nicholls, J.R. [Cranfield University, Power Generation Technology Centre, Cranfield, Beds, MK43 0AL (United Kingdom)

    2004-07-01

    Gas turbines are at the heart of many modern power systems, with combined cycle power generation utilising natural gas being an effective way of reducing environmental emissions compared to conventional pulverized coal fired plants. The development of gas turbine technology has been focused on increasing its efficiency. However, the lives of the hot gas path components within these gas turbines are also critical to the viability of the power systems. Single crystal superalloys have been developed for use with clean fuel/air but are now being used in industrial gas turbines that may need to run with dirtier fuel/air. Indeed, gas turbine based power systems are being evaluated in which solid fuels (e.g. coal and/or biomass) are gasified to produce fuel gases, which introduces the potential for significant corrosive and erosive damage to gas turbine blades and vanes. The performance of these materials, with coatings, has to be determined before they can be used with confidence in dirtier fuel environments. This paper reports results from a series of laboratory tests carried out using the 'deposit replenishment' technique to investigate the sensitivity of candidate materials to exposure conditions anticipated in such gas turbines. The materials investigated have included CMSX-4 and SC{sup 2}-B (both bare and with Pt-Al and Amdry 997 coatings) as well as conventional nickel based superalloys such as IN738LC for comparison. The exposure conditions within the laboratory tests have covered ranges of SO{sub x} (50 and 500 vpm) and HCl (0 and 500 vpm) in air, as well as 4/1 (Na/K){sub 2}SO{sub 4} deposits, with deposition fluxes of 1.5, 5 and 15 {mu}g/cm{sup 2}/h, for periods of up to 500 hours at 700 and 900 deg. C. Data on the performance of materials has been obtained using dimensional metrology: pre-exposure contact measurements and post-exposure measurements of features on polished cross-sections. These measurement methods allow distributions of damage data to

  10. Lattice QCD on fine lattices

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, Stefan [DESY (Germany). Neumann Inst. for Computing

    2016-11-01

    These configurations are currently in use in many on-going projects carried out by researchers throughout Europe. In particular this data will serve as an essential input into the computation of the coupling constant of QCD, where some of the simulations are still on-going. But also projects computing the masses of hadrons and investigating their structure are underway as well as activities in the physics of heavy quarks. As this initial project of gauge field generation has been successful, it is worthwhile to extend the currently available ensembles with further points in parameter space. These will allow to further study and control systematic effects like the ones introduced by the finite volume, the non-physical quark masses and the finite lattice spacing. In particular certain compromises have still been made in the region where pion masses and lattice spacing are both small. This is because physical pion masses require larger lattices to keep the effects of the finite volume under control. At light pion masses, a precise control of the continuum extrapolation is therefore difficult, but certainly a main goal of future simulations. To reach this goal, algorithmic developments as well as faster hardware will be needed.

  11. Advanced Ni base superalloys for small gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Wahl, J.B.; Harris, K.

    2011-07-15

    Nickel base superalloy materials have extensive applications in the hot turbine section of aero and industrial gas turbine engines. They provide a unique combination of characteristics suitable for higher temperature strength and durability requirements and are also applicable to small turbine and missile engines. Specific considerations pertinent to selection of superalloys for small gas turbine engines include not only overall mechanical properties, but also the changes in properties over time due to operation, reduction in properties for thin wall applications compared to thick section database values, alloy density and the effect on disc and shaft alloy selection, and always, material/component costs. Nickel base superalloys were first introduced into military gas turbine engines during the Second World War and the technology has advanced dramatically since that time, including conventionally cast equiax (EQ) alloys, directionally solidified (DS) and single crystal (SX) cast components. This paper discusses the characteristics and applications of each casting technology.

  12. Deformation Behavior of Hot Isostatic Pressing FGH96 Superalloy

    Institute of Scientific and Technical Information of China (English)

    LIU Yuhong; LI Fuguo; YU Hongbo

    2006-01-01

    The deformation behavior of hot isostatic pressing (HIP) FGH96 superalloy was characterized in the temperature range of 1 000-1 100 ℃ and strain rate range of 0. 001-0.1 s-1 using hot compression testing. The flow curves of HIP FGH96 superalloy during hot deformation was analyzed systematically. The results show that deformation temperature, strain rate and strain are the main influence factors on flow stress of HIP FGH96 superalloy during hot deformation. The flow stress displays a peak at a critical strain and then decreases with further increase in strain. For a given strain, the flow stress decreases with the increase of deformation temperature, and increases with the increase of strain rate. A mathematical model of these flow curves was established through regression analysis and taking the strain as a modification factor. The calculated stress values agree well with the experimental values.

  13. Evaluation of powder metallurgy superalloy disk materials

    Science.gov (United States)

    Evans, D. J.

    1975-01-01

    A program was conducted to develop nickel-base superalloy disk material using prealloyed powder metallurgy techniques. The program included fabrication of test specimens and subscale turbine disks from four different prealloyed powders (NASA-TRW-VIA, AF2-1DA, Mar-M-432 and MERL 80). Based on evaluation of these specimens and disks, two alloys (AF2-1DA and Mar-M-432) were selected for scale-up evaluation. Using fabricating experience gained in the subscale turbine disk effort, test specimens and full scale turbine disks were formed from the selected alloys. These specimens and disks were then subjected to a rigorous test program to evaluate their physical properties and determine their suitability for use in advanced performance turbine engines. A major objective of the program was to develop processes which would yield alloy properties that would be repeatable in producing jet engine disks from the same powder metallurgy alloys. The feasibility of manufacturing full scale gas turbine engine disks by thermomechanical processing of pre-alloyed metal powders was demonstrated. AF2-1DA was shown to possess tensile and creep-rupture properties in excess of those of Astroloy, one of the highest temperature capability disk alloys now in production. It was determined that metallographic evaluation after post-HIP elevated temperature exposure should be used to verify the effectiveness of consolidation of hot isostatically pressed billets.

  14. Metallurgical optimisation of PM superalloy N19

    Directory of Open Access Journals (Sweden)

    Locq Didier

    2014-01-01

    Full Text Available Microstructures of the new PM superalloy N19 have been investigated for various heat treatments in order to reach the best compromise between static strength and cyclic resistance. One subsolvus and several supersolvus heat treatments were applied to produce fine (7 μm and medium (25 μm grain sizes, respectively. The alloy is shown to be quite sensitive to the cooling conditions after solutioning as the γ′ hardening precipitates, both secondary and tertiary, have a direct influence on mechanical properties. Two cooling conditions after solutioning produce a high crack propagation resistance at 650 °C with dwell time cycles, which is one of the basic requirements. The low cycle fatigue behaviour appears to be correlated to the grain size, which determines the origin of crack initiation (from ceramic inclusions or not. The other mechanical properties (tensile, creep remain above target levels. Despite the medium size grain microstructure in the supersolvus condition, a high level of mechanical strength is observed in N19 at elevated temperature. It is understood that further improvement in properties can be achieved by developing coarse grain microstructures.

  15. Metallurgical modelling of superalloy disc isothermal forgings

    Science.gov (United States)

    Evans, R. W.

    1988-08-01

    The metallurgical structure of superalloy aeroengine disc forgings is a complex function of the forging operation parameters and the post forging heat treatment. It is often desirable to obtain certain specific structures in parts of the disc which are, for instance, resistant to crack propagation and this has traditionally been accomplished by means of a series of production trials. This expensive and time consuming procedure can be considerably shortened if the development of microstructure during the forging can be accurately modelled by a suitable computer code. Described here is such a model and its use in the design of isothermal forged components. The model discribed is a fully thermally coupled viscoplasticity finite element algorithm. It treats nodal velocities as the basic unknowns and both the mesh geometry and the various metallurgical structural terms are updated by a single step Euler scheme. Facilities are available for ensuring that surface nodes follow die shapes after impingement, that flow is incompressible and that suitable surface friction forces are applied. Throughout the whole forging process (which may involve the re-meshing of severely distorted elements), the metallurgical history of elements is retained so that the effects of subsequent heat treatments can be assessed.

  16. Lubrication in Hot Tube Extrusion of Superalloys and Ti Alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Tubular products made of superalloys and titanium alloys usually work in high temperature environment and applied heavy loading. Hot extrusion is the best technology to form tubular billets with fine microstructures and good mechanical properties. Lubrication is one of the key techniques in hot extrusion, glass lubricants are most suitable for hot extrusion. Lubrication technique in hot extrusion is dealt with in this paper, the lubrication principle of hot tube extrusion is presented. Experiments of glass lubricated backward tube extrusion of titanium alloys and forward tube extrusion of superalloys are also discussed.

  17. Solidification microstructure of directionally solidified superalloy under high temperature gradient

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The effect of solidification rate on the microstructure development of nickel-based superalloy under the temperature gradient of 500 K·cm-1 was studied. The results show that, with the increase of directional solidification rate from 50 to 800 μm·s-1, both the primary and the secondary dendrite arm spacings of the alloy decrease gradually, and the dendrite morphologies transform from coarse dendrite to superfine dendrite. The sizes of all precipitates in the superalloy decrease gradually. The morphology of ...

  18. Recrystallizaiton Behavior of Directionally Solidified DZ4 Superalloy

    Institute of Scientific and Technical Information of China (English)

    Li Yun-ju; Zhang Wei-fang; Tao Chun-hu

    2004-01-01

    This article investigated effects of degrees of deformation, heat treatment temperatures and holding times on the recrystallization behavior of directionally solidified DZ4 superalloy. The results showed that, recrystallization of DZ4 superalloy could take place during solution heat treatment after certain degrees of cold work and depths of recrystallization increased with increasing degrees of deformation and heat treatment temperature. At the temperature below γ' solvus,prolonged holding times did not play an important role in improving recrystallization depths. Moreover, prevention measures for recrystallization of directionally solidified blades were given.

  19. Dual Lattice of ℤ-module Lattice

    Directory of Open Access Journals (Sweden)

    Futa Yuichi

    2017-07-01

    Full Text Available In this article, we formalize in Mizar [5] the definition of dual lattice and their properties. We formally prove that a set of all dual vectors in a rational lattice has the construction of a lattice. We show that a dual basis can be calculated by elements of an inverse of the Gram Matrix. We also formalize a summation of inner products and their properties. Lattice of ℤ-module is necessary for lattice problems, LLL(Lenstra, Lenstra and Lovász base reduction algorithm and cryptographic systems with lattice [20], [10] and [19].

  20. Rock blocks

    OpenAIRE

    Turner, W.

    2007-01-01

    Consider representation theory associated to symmetric groups, or to Hecke algebras in type A, or to q-Schur algebras, or to finite general linear groups in non-describing characteristic. Rock blocks are certain combinatorially defined blocks appearing in such a representation theory, first observed by R. Rouquier. Rock blocks are much more symmetric than general blocks, and every block is derived equivalent to a Rock block. Motivated by a theorem of J. Chuang and R. Kessar in the case of sym...

  1. Negative creep in nickel base superalloys

    DEFF Research Database (Denmark)

    Dahl, Kristian Vinter; Hald, John

    2004-01-01

    Negative creep describes the time dependent contraction of a material as opposed to the elongation seen for a material experiencing normal creep behavior. Negative creep occurs because of solid state transformations that results in lattice contractions. For most applications negative creep will h...

  2. Continuous Extraction of Nickel from Superalloy Scraps Using Zinc Circulation

    Science.gov (United States)

    Yagi, Ryohei; Okabe, Toru H.

    2017-02-01

    A novel technique for the continuous extraction of nickel (Ni) from Ni-based superalloy scraps using molten zinc (Zn) has been proposed, and its feasibility was experimentally demonstrated. The newly developed approach allows for extraction of Ni metal directly from superalloy scraps with simultaneous separation of the Zn from the resulting Zn-Ni alloy. The optimal conditions for the extraction of Ni and separation of valuable elements such as rhenium (Re), tantalum (Ta), and tungsten (W) were determined by varying major process parameters including the reaction time and configuration of the reaction chamber. The proposed method has been successfully utilized for the production of the superalloy containing 62.8 mass pct of Ni and 15.5 mass pct of refractory metals (Re, W, and Ta). Under certain conditions, 41 pct of the Ni contained in the superalloy could be extracted at 1173 K (900 °C) over 48 hours, producing an alloy containing 84.0 mass pct of Ni and 0.2 mass pct of the refractory metals.

  3. Deformation, fatigue and fracture behavior of two cast anisotropic superalloys

    Science.gov (United States)

    Milligan, Walter W.; Huron, Eric S.; Antolovich, Stephen D.

    1987-01-01

    Tensile and low cycle fatigue (LCF) tests were conducted on two cast anisotropic superalloys. The effects of temperature, strain rate and stress range were investigated. Deformation behavior was extensively characterized and modeled. LCF and fracture behavior were studied and correlated with deformation behavior.

  4. Nickel-Based Superalloy Resists Embrittlement by Hydrogen

    Science.gov (United States)

    Lee, Jonathan; Chen, PoShou

    2008-01-01

    A nickel-based superalloy that resists embrittlement by hydrogen more strongly than does nickel alloy 718 has been developed. Nickel alloy 718 is the most widely used superalloy. It has excellent strength and resistance to corrosion as well as acceptably high ductility, and is recognized as the best alloy for many high-temperature applications. However, nickel alloy 718 is susceptible to embrittlement by hydrogen and to delayed failure and reduced tensile properties in gaseous hydrogen. The greater resistance of the present nickel-based superalloy to adverse effects of hydrogen makes this alloy a superior alternative to nickel alloy 718 for applications that involve production, transfer, and storage of hydrogen, thereby potentially contributing to the commercial viability of hydrogen as a clean-burning fuel. The table shows the composition of the present improved nickel-based superalloy in comparison with that of nickel alloy 718. This composition was chosen to obtain high resistance to embrittlement by hydrogen while maintaining high strength and exceptional resistance to oxidation and corrosion. The most novel property of this alloy is that it resists embrittlement by hydrogen while retaining tensile strength greater than 175 kpsi (greater than 1.2 GPa). This alloy exhibits a tensile elongation of more than 20 percent in hydrogen at a pressure of 5 kpsi (approximately equal to 34 MPa) without loss of ductility. This amount of elongation corresponds to 50 percent more ductility than that exhibited by nickel alloy 718 under the same test conditions.

  5. 76 FR 8773 - Superalloy Degassed Chromium From Japan

    Science.gov (United States)

    2011-02-15

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Superalloy Degassed Chromium From Japan AGENCY: United States International Trade Commission... Japan would be likely to lead to continuation or recurrence of material injury. On December 22, 2010...

  6. Improved Lattice Renormalization Group Techniques

    CERN Document Server

    Petropoulos, Gregory; Hasenfratz, Anna; Schaich, David

    2013-01-01

    We compute the bare step-scaling function $s_b$ for SU(3) lattice gauge theory with $N_f = 12$ massless fundamental fermions, using the non-perturbative Wilson-flow-optimized Monte Carlo Renormalization Group two-lattice matching technique. We use a short Wilson flow to approach the renormalized trajectory before beginning RG blocking steps. By optimizing the length of the Wilson flow, we are able to determine an $s_b$ corresponding to a unique discrete $\\beta$ function, after a few blocking steps. We carry out this study using new ensembles of 12-flavor gauge configurations generated with exactly massless fermions, using volumes up to $32^4$. The results are consistent with the existence of an infrared fixed point (IRFP) for all investigated lattice volumes and number of blocking steps. We also compare different renormalization schemes, each of which indicates an IRFP at a slightly different value of the bare coupling, as expected for an IR-conformal theory.

  7. Perfect Lattice Actions for Staggered Fermions

    CERN Document Server

    Bietenholz, W; Chandrasekharan, S; Wiese, U J

    1996-01-01

    We construct a perfect lattice action for staggered fermions by blocking from the continuum. The locality, spectrum and pressure of such perfect staggered fermions are discussed. We also derive a consistent fixed point action for free gauge fields and discuss its locality as well as the resulting static quark-antiquark potential. This provides a basis for the construction of (classically) perfect lattice actions for QCD using staggered fermions.

  8. Construction of Capacity Achieving Lattice Gaussian Codes

    KAUST Repository

    Alghamdi, Wael

    2016-04-01

    We propose a new approach to proving results regarding channel coding schemes based on construction-A lattices for the Additive White Gaussian Noise (AWGN) channel that yields new characterizations of the code construction parameters, i.e., the primes and dimensions of the codes, as functions of the block-length. The approach we take introduces an averaging argument that explicitly involves the considered parameters. This averaging argument is applied to a generalized Loeliger ensemble [1] to provide a more practical proof of the existence of AWGN-good lattices, and to characterize suitable parameters for the lattice Gaussian coding scheme proposed by Ling and Belfiore [3].

  9. Automated Identification and Characterization of Secondary & Tertiary gamma’ Precipitates in Nickel-Based Superalloys (PREPRINT)

    Science.gov (United States)

    2010-01-01

    METHODOLOGY A nickel-based superalloy sample (Rene88DT) was cut from a forged disc developed under a Defense Advanced Research Projects Agency funded...AFRL-RX-WP-TP-2010-4064 AUTOMATED IDENTIFICATION AND CHARACTERIZATION OF SECONDARY & TERTIARY γ’ PRECIPITATES IN NICKEL-BASED SUPERALLOYS ...AUTOMATED IDENTIFICATION AND CHARACTERIZATION OF SECONDARY & TERTIARY γ’ PRECIPITATES IN NICKEL-BASED SUPERALLOYS (PREPRINT) 5a. CONTRACT NUMBER In

  10. Effect of Electromagnetic Stirring on the Quality of K417 Superalloy Ingots

    Institute of Scientific and Technical Information of China (English)

    Jin; Wenzhong; Li; Tingju; Yin; Guomao

    2007-01-01

    The effect of electromagnetic stirring on the inner quality of K417 superalloy ingots is studied with EPMA and optical microscope.The results show that while an electromagnetic stirring with 50Hz frequency and 80A current is imposed,the equiax crystals of K417 superalloy ingots can be effectively refined and increased,and the central shrinkage porosity and the dendritic segregation of K417 superalloy ingots are greatly reduced,so the inner quality of K417 superalloy ingots is obviously improved.

  11. Recent trends in superalloys research for critical aero-engine components

    Energy Technology Data Exchange (ETDEWEB)

    Remy, Luc [Mine ParisTech, CNRS UMR 7633, 91 - Evry (France). Centre des Materiaux; Guedou, Jean-Yves [Snecma Safran Group, Moissy-Cramayel (France). Materials and Processes Dept.

    2010-07-01

    This paper is a brief survey of common research activity on superalloys for aero-engines between Snecma and Mines ParisTech Centre des Materiaux during recent years. First in disks applications, the development of new powder metallurgy superalloys is shown. Then grain boundary engineering is investigated in a wrought superalloy. Secondly, design oriented research on single crystals blades is shown: a damage model for low cycle fatigue is used for life prediction when cracks initiated at casting pores. The methodology developed for assessing coating life is illustrated for thermal barrier coating deposited on AMI single crystal superalloy. (orig.)

  12. Interfacial Dislocation Networks and Creep in Directional Coarsened Ru-Containing Nickel-Base Single-Crystal Superalloys

    Science.gov (United States)

    Carroll, L. J.; Feng, Q.; Pollock, T. M.

    2008-06-01

    Mechanisms of creep deformation in nickel-base superalloy single crystals in the directional coarsening regime have been studied in alloys with large variations in γ- γ' lattice misfit and phase composition, achieved by Ru additions and variable levels of Cr and Co. Interfacial dislocation spacings established by long-term annealing experiments under no externally applied stress indicate that the experimental alloys have high-temperature lattice misfits ranging from near-zero to as large as -0.65 pct. Variation in misfit influences the stress-induced directional coarsening (rafting) behavior during creep deformation at 950 °C and 290 MPa. In postcreep deformed material, the density of excess dislocations (defined as the dislocations beyond those necessary to relieve the lattice misfit) at the γ- γ' interfaces varied with alloy composition, with the most creep-resistant alloy containing the highest excess interfacial dislocation density. In the directional coarsening creep regime, continued deformation requires shearing of the γ' rafts and is strongly influenced by the resistance of the precipitates to shearing as well as the interfacial dislocation structure. A preliminary model for creep in the rafting regime is developed.

  13. The influence of cobalt, tantalum, and tungsten on the microstructure of single crystal nickel-base superalloys

    Science.gov (United States)

    Nathal, M. V.; Ebert, L. J.

    1985-10-01

    The influence of composition on the microstructure of single crystal nickel-base superalloys was investigated. Co was replaced by Ni, and Ta was replaced by either Ni or W, according to a matrix of compositions based on MAR-M247. Substitution of Ni for Co caused an increase in γ' solvus temperature, an increase in γ-γ' lattice mismatch, and the precipitation of W-rich phases in the alloys with high refractory metal levels. Substitution of Ni for Ta caused large decreases in γ' solvus temperature, γ' volume fraction, and γ-γ' lattice mismatch, whereas substitution of W for Ta resulted in smaller decreases in these features. For the alloys with γ' particles that remained coherent, substitution of Ni for Co caused an increase in γ' coarsening rate. The two alloys with the largest magnitude of lattice mismatch possessed γ' particles which lost coherency during unstressed aging and exhibited anomalously low coarsening rates. Creep exposure at 1000 °C resulted in the formation of γ' lamellae oriented perpendicular to the applied stress axis in all alloys.

  14. Free µ-Lattices

    DEFF Research Database (Denmark)

    Santocanale, Luigi

    2002-01-01

    A μ-lattice is a lattice with the property that every unary polynomial has both a least and a greatest fix-point. In this paper we define the quasivariety of μ-lattices and, for a given partially ordered set P, we construct a μ-lattice JP whose elements are equivalence classes of games in a preor...

  15. Population Blocks.

    Science.gov (United States)

    Smith, Martin H.

    1992-01-01

    Describes an educational game called "Population Blocks" that is designed to illustrate the concept of exponential growth of the human population and some potential effects of overpopulation. The game material consists of wooden blocks; 18 blocks are painted green (representing land), 7 are painted blue (representing water); and the remaining…

  16. Population Blocks.

    Science.gov (United States)

    Smith, Martin H.

    1992-01-01

    Describes an educational game called "Population Blocks" that is designed to illustrate the concept of exponential growth of the human population and some potential effects of overpopulation. The game material consists of wooden blocks; 18 blocks are painted green (representing land), 7 are painted blue (representing water); and the remaining…

  17. Characteristics of GTA fusion zones and heat affected zones in superalloy 713C

    Science.gov (United States)

    Lachowicz, M. B.; Dudziński, W.

    2012-09-01

    In this paper, metallographic examinations, characterising microstructural changes in the 713C superalloy subjected to remelting by GTA method, are presented. In the fusion zone, precipitation of M23C6 or M6C carbides based on chromium and molybdenum was observed. Eutectic mixtures of ( γ- gg')-M x C y type with highly developed morphology were also perceived. It was found that, in the matrix areas with non-homogeneous chemical composition, the eutectic reaction γ-γ' can occur at the temperature close to that of the precipitation of the M x C y carbides. The presence of silicon in the carbide phases can be conducive to lowering their solidification point by creating low-melting compound NbSi. Both in the fusion zone (FZ) and in the heat-affected zone (HAZ), the secondary precipitates of the Ni3(AlTi)- γ' phase, varying in size from 50 to 100 nm, were found. The lattice mismatch factor of the γ and γ' particles was +0.48 % to +0.71 %, which is characteristic of the coherent precipitates of the Ni3Al phase enriched with titanium. No dislocations or stacking faults were observed in the microstructure of the FZ. In the HAZ, some primary undissolved γ' precipitates, with a part of aluminium probably replaced with niobium were observed, which raised their melting point.

  18. Broaching Performance of Superalloy GH4169 Based on FEM

    Institute of Scientific and Technical Information of China (English)

    Xiangwei Kong; Bin Li; Zhibo Jin; Wenran Geng

    2011-01-01

    The nickel-based superalloy GH4169 is an important material for high temperature applications in the aerospace industry. However, due to its poor machinability, GH4169 is hard to be cut and generates saw-tooth chips during high speed machining, which could significantly affect the dynamic cutting force, cutting temperature fluctuation, tool life, and the surface integrity of the parts. In this paper, the saw-tooth chip formation mechanism of superalloy GH4169 was investigated by the elasto-viscoplastic finite element method (FEM). Using the finite element software of ABAQUS/Explicit, the deformation of the part during high speed machining was simulated. The effective plastic strain, the temperature field, the stress distribution, and the cutting force were analyzed to determine the influence of the cutting parameters on the saw-tooth chip formation. The study on broaching performance has great effect on selecting suitable machining parameters and improving tool life.

  19. Feasibility Study for Casting of High Temperature Refractory Superalloy Composites

    Science.gov (United States)

    Lee, Jonathan A.

    1998-01-01

    Abstract This study investigated the feasibility of using conventional casting technique to fabricate refractory wires reinforced superalloy composites. These composites were being developed for advanced rocket engine turbine blades and other high temperature applications operating up to 2000 F. Several types of refractory metal wires such as W- Th, W-Re, Mo-Hf-C and W-HF-C reinforced waspaloy were experimentally cast and heat treated at 2000 F up to 48 hrs. Scanning electron microscope analysis was conducted in regions adjacent to the wire-matrix interface to determine the reaction zone and chemical compatibility resulting from material interdiffusion. It was concluded that fabrication using conventional casting may be feasible because the wire-matrix reaction zone thickness was comparable to similar composites produced by arc-sprayed monotape with hot isostatic pressing technique, Moreover, it was also found that the chemical compatibility could be improved significantly through a slight modification of the superalloy matrix compositions.

  20. Powder-metallurgy superalloy strengthened by a secondary gamma phase.

    Science.gov (United States)

    Kotval, P. S.

    1971-01-01

    Description of experiments in which prealloyed powders of superalloy compositions were consolidated by extrusion after the strengthening by precipitation of a body-centered tetragonal gamma secondary Ni3 Ta phase. Thin foil electron microscopy showed that the mechanical properties of the resultant powder-metallurgy product were correlated with its microstructure. The product exhibited high strength at 1200 F without loss of ductility, after thermomechanical treatment and aging.

  1. Surface modification, microstructure and mechanical properties of investment cast superalloy

    OpenAIRE

    M. Zielińska; Kubiak, K.; J. Sieniawski

    2009-01-01

    Purpose: The aim of this work is to determine physical and chemical properties of cobalt aluminate (CoAl2O4) modifiers produced by different companies and the influence of different types of modifiers on the grain size, the microstructure and mechanical properties of high temperature creep resisting superalloy René 77.Design/methodology/approach: The first stage of the research work took over the investigations of physical and chemical properties of cobalt aluminate manufactured by three diff...

  2. Potential of Metal-Matrix Composites as Superalloy Substitutes

    Science.gov (United States)

    1984-04-01

    Engine Construction. Towards a Cycle without Loss: Cobalt in the Aircraft Industry. Gas Turbine Engine Design Considerations as Related to Alloys of...Developments to Reduce Strategic Materials Usage. Practical Implications of the Use of Alumlnlde Coatings for the Corrosion Protection of Superalloys in Gas ...Aaroapatlalas (ONERA) BP72, 92)22 Chatlllon, Cadax, Franca ABSTRACT ’The potential of metal-matrlx coaposltas aa qaa- turbina blada material« has

  3. Constitutive Equation of Superalloy In718 in Hammer Forging Process

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A constitutive equation reflecting the flow behavior ofSuperalloy In718 during the counter-blow hammer forging process was developed in terms of the relationship of flow stress and hot-deformation parameters, such as strain, strain rate, and deformation temperature. A new simplified approach for the complex multi-pass stress-strain curves has been attempted. The simulation curves calculated by constitutive equation are consistent with the experimental data.

  4. Chaotic and ballistic dynamics in time-driven quasiperiodic lattices.

    Science.gov (United States)

    Wulf, Thomas; Schmelcher, Peter

    2016-04-01

    We investigate the nonequilibrium dynamics of classical particles in a driven quasiperiodic lattice based on the Fibonacci sequence. An intricate transient dynamics of extraordinarily long ballistic flights at distinct velocities is found. We argue how these transients are caused and can be understood by a hierarchy of block decompositions of the quasiperiodic lattice. A comparison to the cases of periodic and fully randomized lattices is performed.

  5. Sphere Lower Bound for Rotated Lattice Constellations in Fading Channels

    CERN Document Server

    Fabregas, Albert Guillen i

    2007-01-01

    We study the error probability performance of rotated lattice constellations in frequency-flat Nakagami-$m$ block-fading channels. In particular, we use the sphere lower bound on the underlying infinite lattice as a performance benchmark. We show that the sphere lower bound has full diversity. We observe that optimally rotated lattices with largest known minimum product distance perform very close to the lower bound, while the ensemble of random rotations is shown to lack diversity and perform far from it.

  6. Chaotic and ballistic dynamics in time-driven quasiperiodic lattices

    CERN Document Server

    Wulf, Thomas

    2016-01-01

    We investigate the nonequilibrium dynamics of classical particles in a driven quasiperiodic lattice based on the Fibonacci sequence. An intricate transient dynamics of extraordinarily long ballistic flights at distinct velocities is found. We argue how these transients are caused and can be under- stood by a hierarchy of block decompositions of the quasiperiodic lattice. A comparison to the cases of periodic and fully randomized lattices is performed.

  7. Chaotic and ballistic dynamics in time-driven quasiperiodic lattices

    Science.gov (United States)

    Wulf, Thomas; Schmelcher, Peter

    2016-04-01

    We investigate the nonequilibrium dynamics of classical particles in a driven quasiperiodic lattice based on the Fibonacci sequence. An intricate transient dynamics of extraordinarily long ballistic flights at distinct velocities is found. We argue how these transients are caused and can be understood by a hierarchy of block decompositions of the quasiperiodic lattice. A comparison to the cases of periodic and fully randomized lattices is performed.

  8. Phase transformation strengthening of high-temperature superalloys

    Science.gov (United States)

    Smith, T. M.; Esser, B. D.; Antolin, N.; Carlsson, A.; Williams, R. E. A.; Wessman, A.; Hanlon, T.; Fraser, H. L.; Windl, W.; McComb, D. W.; Mills, M. J.

    2016-11-01

    Decades of research has been focused on improving the high-temperature properties of nickel-based superalloys, an essential class of materials used in the hot section of jet turbine engines, allowing increased engine efficiency and reduced CO2 emissions. Here we introduce a new `phase-transformation strengthening' mechanism that resists high-temperature creep deformation in nickel-based superalloys, where specific alloying elements inhibit the deleterious deformation mode of nanotwinning at temperatures above 700 °C. Ultra-high-resolution structure and composition analysis via scanning transmission electron microscopy, combined with density functional theory calculations, reveals that a superalloy with higher concentrations of the elements titanium, tantalum and niobium encourage a shear-induced solid-state transformation from the γ' to η phase along stacking faults in γ' precipitates, which would normally be the precursors of deformation twins. This nanoscale η phase creates a low-energy structure that inhibits thickening of stacking faults into twins, leading to significant improvement in creep properties.

  9. Property Enrichment of Aged Nickel Base Superalloy Supercast 247A

    Directory of Open Access Journals (Sweden)

    Lavakumar Avala

    2013-12-01

    Full Text Available The commercial nickel-base superalloy Supercast 247A can be used for applications in which is required high mechanical strength and corrosion resistance at elevated temperatures, such as turbine blades and automotive turbocharger rotors. The mechanical properties are totally connected to the morphology, size and distribution of γ' phase and carbides. In order to improve the mechanical properties, the material is subjected to solution and aging heat treatment, to raise the volume fraction of γ' phase in the matrix and to form carbides at grain boundaries. In the present study the Supercast 247A superalloy was remelted and cast to obtain the desired polycrystalline test bars by controlling casting parameters, followed by the investigation of precipitation morphology and mechanical properties with respect to solution treatment and aging treatment. The experimental results show that by well controlled casting parameters the Supercast 247A owns excellent castability to form a superalloy with fine grain structure, resistance to indentation as well as superior strength.

  10. Processing-structure characterization of rheocast IN-100 superalloy

    Science.gov (United States)

    Cheng, Jung-Jen Allen; Apelian, Diran; Doherty, Roger D.

    1986-11-01

    The rheocasting solidification process has been applied in the production of IN-100 nickel base superalloy. A high vacuum furnace for rheocasting superalloys was used to rheocast ingots under different processing conditions. Processing variables which were evaluated include stirring speed, isothermal stirring time, and volume fraction solid during isothermal stirring. Ingots, furnace cooled at the same rate but without stirring, were also examined for comparison with the rheocast ingots. A detailed microstructural examination was made of the resultant microstructure both on furnace cooling after stirring and on reheating to the isothermal stirring temperature followed by water quenching. Rheocasting yielded fine-grained structures, where the extent of microsegregatiori, the variation in macrostructure, and the solidification-induced porosity were found to be reduced in comparison to the unstirred ingot. The grain size and nonuniformity in the as-cast ingot were reduced by increasing the stirring speed, isothermal stirring time, or the volume fraction solid during stirring. The degree of the microsegregation decreased significantly with increasing volume fraction solid. Grain boundaries, both with and without solute enrichment, were found in the rosette-like solid particles after rheocasting, lending support to the Vogel-Cantor-Doherty model of rheocasting based on the formation of grain boundaries by strain-induced recrystallization and by sintering. It is clear from these results that the microstructure of this superalloy was significantly improved by rheocasting. Improved mechanical properties were also found and will be reported separately.

  11. Gas metal arc welding in refurbishment of cobalt base superalloys

    Science.gov (United States)

    Shahriary, M. S.; Miladi Gorji, Y.; Kolagar, A. M.

    2017-01-01

    Refurbishments of superalloys which are used in manufacturing gas turbine hot components usually consists of removing cracks and other defects by blending and then repair welding in order to reconstruct damaged area. In this study, the effects of welding parameters on repair of FSX-414 superalloy, as the most applicable cobalt base superalloy in order to manufacture gas turbine nozzles, by use of Gas Metal Arc Welding (GMAW) technic were investigated. Results then were compared by Gas Tungsten Arc Welding (GTAW). Metallographic and SEM studies of the microstructure of the weld and HAZ showed that there are no noticeable defects in the microstructure by use of GMAW. Also, chemical analysis and morphologies of carbide in both methods are similar. Hardness profile of the GM AW structure then also compared with GTAW and no noticeable difference was observed between the profiles. Also, proper tensile properties, compared with GTAW, can be achieved by use of optimum parameters that can be obtained by examining the current and welding speed. Tensile properties of optimized condition of the GMAW then were compared with GTAW. It was seen that the room and high temperature tensile properties of the GMAW structure is very similar and results confirmed that changing the technic did not have any significant influence on the properties.

  12. NASA and Superalloys: A Customer, a Participant, and a Referee

    Science.gov (United States)

    Nathal, Michael V.

    2008-01-01

    NASA has had a long history of research and development in the field of superalloys. These efforts have continued today, where the latest advancements in turbine disk and blade technologies are being developed Although NASA does support military flight systems, it s predominant role is in supporting civilian air transportation systems, and thus has goals for improving fuel efficiency, emissions, noise, and safety of today s aircraft. NASA has traditionally served several distinct but complimentary roles as participants in multi-disciplinary research teams, as customers who fund research and development efforts at industry and universities, and as referees who can address broad issues that affect the entire aeronautics community. Because of our longer range viewpoint, we can take on higher risk, higher reward research topics. NASA can also serve as an intermediary between the basic research performed primarily at universities and the development efforts emphasized by industry. By interacting with individual companies, NASA can identify areas of general interest and problems common to a large portion of the aeronautics community, and devise programs aimed at solving these problems. In space missions, NASA is a direct customer responsible for developing vehicles. In the case of the Space Shuttle, NASA has worked with various contractors to design and build numerous components out of superalloys. Another fascinating area for the use of superalloys is in power systems for long life applications in space. Potential missions include providing electric power for deep space missions, surface rovers, including lunar and Mars, and stationary power generators on the lunar surface.

  13. Exploring Proton Structure Using Lattice Qcd

    CERN Document Server

    Renner, D B

    2004-01-01

    We calculate moments of the generalized parton distributions of the nucleon using lattice QCD. The generalized parton distributions determine the angular momentum decomposition of the nucleon and the transverse distributions of partons within the nucleon. Additionally, the generalized parton distributions reduce to the elastic form factors and ordinary parton distributions in particular kinematic limits. Thus by calculating moments of the generalized parton distributions in lattice QCD we can explore many facets of the structure of the nucleon. In this effort, we have developed the building block method to determine all the lattice correlation functions which contribute to the off forward matrix elements of the twist two operators. These matrix elements determine the generalized form factors of the nucleon which in turn give the moments of the generalized parton distributions. Thus we use our building block method to calculate all the matrix elements of the lowest twist two operators. Furthermore, we use our ...

  14. The Mechanical Properties of Candidate Superalloys for a Hybrid Turbine Disk

    Science.gov (United States)

    Gabb, Timothy P.; MacKay, Rebecca A.; Draper, Susan L.; Sudbrack, Chantal K.; Nathal, Michael V.

    2013-01-01

    The mechanical properties of several cast blade superalloys and one powder metallurgy disk superalloy were assessed for potential use in a dual alloy hybrid disk concept of joined dissimilar bore and web materials. Grain size was varied for each superalloy class. Tensile, creep, fatigue, and notch fatigue tests were performed at 704 to 815 degC. Typical microstructures and failure modes were determined. Preferred materials were then selected for future study as the bore and rim alloys in this hybrid disk concept. Powder metallurgy superalloy LSHR at 15 micron grain size and single crystal superalloy LDS-1101+Hf were selected for further study, and future work is recommended to develop the hybrid disk concept.

  15. Ultralocality on the lattice

    CERN Document Server

    Campos, R G; Campos, Rafael G.; Tututi, Eduardo S.

    2002-01-01

    It is shown that the nonlocal Dirac operator yielded by a lattice model that preserves chiral symmetry and uniqueness of fields, approaches to an ultralocal and invariant under translations operator when the size of the lattice tends to zero.

  16. New integrable lattice hierarchies

    Energy Technology Data Exchange (ETDEWEB)

    Pickering, Andrew [Area de Matematica Aplicada, ESCET, Universidad Rey Juan Carlos, c/ Tulipan s/n, 28933 Mostoles, Madrid (Spain); Zhu Zuonong [Departamento de Matematicas, Universidad de Salamanca, Plaza de la Merced 1, 37008 Salamanca (Spain) and Department of Mathematics, Shanghai Jiao Tong University, Shanghai 200030 (China)]. E-mail: znzhu2@yahoo.com.cn

    2006-01-23

    In this Letter we give a new integrable four-field lattice hierarchy, associated to a new discrete spectral problem. We obtain our hierarchy as the compatibility condition of this spectral problem and an associated equation, constructed herein, for the time-evolution of eigenfunctions. We consider reductions of our hierarchy, which also of course admit discrete zero curvature representations, in detail. We find that our hierarchy includes many well-known integrable hierarchies as special cases, including the Toda lattice hierarchy, the modified Toda lattice hierarchy, the relativistic Toda lattice hierarchy, and the Volterra lattice hierarchy. We also obtain here a new integrable two-field lattice hierarchy, to which we give the name of Suris lattice hierarchy, since the first equation of this hierarchy has previously been given by Suris. The Hamiltonian structure of the Suris lattice hierarchy is obtained by means of a trace identity formula.

  17. Zitongdong Block

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    @@ The Zitongdong Block (Eastern Zitong Block) is located in the northwest of the Sichuan Basin. Tectonically, it is situated in the east part of Zitong Depression, southeast of mid-Longmenshan folded and faulted belt( as shown on Fig. 8 ), covering an area of 1 730 km2. The traffic is very convenient, the No. 108 national highway passes through the north of the block. Topographically, the area belongs to low hilly land at the elevation of 500-700 m.

  18. GLRT-Optimal Noncoherent Lattice Decoding

    CERN Document Server

    Ryan, Daniel J; Clarkson, I Vaughan L

    2007-01-01

    This paper presents new low-complexity lattice-decoding algorithms for noncoherent block detection of QAM and PAM signals over complex-valued fading channels. The algorithms are optimal in terms of the generalized likelihood ratio test (GLRT). The computational complexity is polynomial in the block length; making GLRT-optimal noncoherent detection feasible for implementation. We also provide even lower complexity suboptimal algorithms. Simulations show that the suboptimal algorithms have performance indistinguishable from the optimal algorithms. Finally, we consider block based transmission, and propose to use noncoherent detection as an alternative to pilot assisted transmission (PAT). The new technique is shown to outperform PAT.

  19. Sober Topological Molecular Lattices

    Institute of Scientific and Technical Information of China (English)

    张德学; 李永明

    2003-01-01

    A topological molecular lattice (TML) is a pair (L, T), where L is a completely distributive lattice and r is a subframe of L. There is an obvious forgetful functor from the category TML of TML's to the category Loc of locales. In this note,it is showed that this forgetful functor has a right adjoint. Then, by this adjunction,a special kind of topological molecular lattices called sober topological molecular lattices is introduced and investigated.

  20. Effect of cooling rate on MC carbide in directionally solidified nickel-based superalloy under high thermal gradient

    Directory of Open Access Journals (Sweden)

    Zhang Weiguo

    2012-02-01

    Full Text Available A series of directional solidification experiments have been performed to study the effect of cooling rate on the precipitation behavior of MC carbide in nickel-based superalloy under the temperature gradient of 500 K·s-1. Results reveal that the morphology of MC carbide changes from coarse block to fine strip, then to Chinese-script, and their sizes reduce gradually with the increasing of cooling rate from 2.53 K·s-1 to 36.4 K·s-1. At low cooling rates, most of these carbides are found to be located at the grain boundary and interdendritic regions, while the coupled growth of some carbides and γ matrix in the center of γ grains is occurred at high cooling rate. The main elements forming MC carbide are Ta, W, and Hf.

  1. Infinite resistive lattices

    NARCIS (Netherlands)

    Atkinson, D; van Steenwijk, F.J.

    The resistance between two arbitrary nodes in an infinite square lattice of:identical resistors is calculated, The method is generalized to infinite triangular and hexagonal lattices in two dimensions, and also to infinite cubic and hypercubic lattices in three and more dimensions. (C) 1999 American

  2. Lattice Regularization and Symmetries

    CERN Document Server

    Hasenfratz, Peter; Von Allmen, R; Allmen, Reto von; Hasenfratz, Peter; Niedermayer, Ferenc

    2006-01-01

    Finding the relation between the symmetry transformations in the continuum and on the lattice might be a nontrivial task as illustrated by the history of chiral symmetry. Lattice actions induced by a renormalization group procedure inherit all symmetries of the continuum theory. We give a general procedure which gives the corresponding symmetry transformations on the lattice.

  3. Accurate determination of lattice parameters based on Niggli reduced cell theory by using digitized electron diffraction micrograph.

    Science.gov (United States)

    Yang, Yi; Cai, Canying; Lin, Jianguo; Gong, Lunjun; Yang, Qibin

    2017-05-01

    In this paper, we used Niggli reduced cell theory to determine lattice constants of a micro/nano crystal by using electron diffraction patterns. The Niggli reduced cell method enhanced the accuracy of lattice constant measurement obviously, because the lengths and the angles of lattice vectors of a primitive cell can be measured directly on the electron micrographs instead of a double tilt holder. With the aid of digitized algorithm and least square optimization by using three digitized micrographs, a valid reciprocal Niggli reduced cell number can be obtained. Thus a reciprocal and real Bravais lattices are acquired. The results of three examples, i.e., Mg4Zn7, an unknown phase (Precipitate phase in nickel-base superalloy) and Ba4Ti13O30 showed that the maximum errors are 1.6% for lengths and are 0.3% for angles.

  4. Determination of solute site occupancies within γ' precipitates in nickel-base superalloys via orientation-specific atom probe tomography.

    Science.gov (United States)

    Meher, S; Rojhirunsakool, T; Nandwana, P; Tiley, J; Banerjee, R

    2015-12-01

    The analytical limitations in atom probe tomography such as resolving a desired set of atomic planes, for solving complex materials science problems, have been overcome by employing a well-developed unique and reproducible crystallographic technique, involving synergetic coupling of orientation microscopy with atom probe tomography. The crystallographic information in atom probe reconstructions has been utilized to determine the solute site occupancies in Ni-Al-Cr based superalloys accurately. The structural information in atom probe reveals that both Al and Cr occupy the same sub-lattice within the L12-ordered γ' precipitates to form Ni3(Al,Cr) precipitates in a Ni-14Al-7Cr (at%) alloy. Interestingly, the addition of Co, which is a solid solution strengthener, to a Ni-14Al-7Cr alloy results in the partial reversal of Al site occupancy within γ' precipitates to form (Ni,Al)3(Al,Cr,Co) precipitates. This unique evidence of reversal of Al site occupancy, resulting from the introduction of other solutes within the ordered structures, gives insights into the relative energetics of different sub-lattice sites when occupied by different solutes.

  5. Comparing the morphology and phase diagram of H-shaped ABC block copolymers and linear ABC block copolymers.

    Science.gov (United States)

    Ye, Xianggui; Yu, Xifei; Sun, Zhaoyan; An, Lijia

    2006-06-22

    By using a combinatorial screening method based on the self-consistent field theory (SCFT) for polymers, we have investigated the morphology of H-shaped ABC block copolymers (A2BC2) and compared them with those of the linear ABC block copolymers. By changing the ratios of the volume fractions of two A arms and two C arms, one can obtain block copolymers with different architectures ranging from linear block copolymer to H-shaped block copolymer. By systematically varying the volume fractions of block A, B, and C, the triangle phase diagrams of the H-shaped ABC block copolymer with equal interactions among the three species are constructed. In this study, we find four different morphologies (lamellar phase (LAM), hexagonal lattice phase (HEX), core-shell hexagonal lattice phase (CSH), and two interpenetrating tetragonal lattice (TET2)). Furthermore, the order-order transitions driven by architectural change are discussed.

  6. Microstructural evolution and castability prediction in newly designed modern third-generation nickel-based superalloys

    Science.gov (United States)

    Naffakh-Moosavy, Homam

    2016-05-01

    The present research aims to establish a quantitative relation between microstructure and chemical composition (i.e., Ti, Al, and Nb) of newly designed nickel-based superalloys. This research attempts to identify an optimum microstructure at which the minimum quantities of γ/γ' and γ/γ″ compounds are achieved and the best castability is predicted. The results demonstrate that the highest quantity of intermetallic eutectics (i.e., 41.5wt%) is formed at 9.8wt% (Ti + Al). A significant quantity of intermetallics formed in superalloy 1 (with a composition of γ - 9.8wt% (Ti + Al)), which can deteriorate its castability. The type and morphology of the eutectics changed and the amount considerably decreased with decreasing Ti + Al content in superalloy 2 (with a composition of γ - 7.6wt% (Ti + Al), 1.5wt% Nb). Thus, it is predicted that the castability would improve for superalloy 2. The same trend was observed for superalloy 4 (with a composition of γ - 3.7wt% (Ti + Al), 4.4wt% Nb). This means that the amount of Laves increases with increasing Nb (to 4.4wt%) and decreasing Ti + Al (to 3.7wt%) in superalloy 4. The best castability was predicted for superalloy 3 (with a composition of γ - 5.7wt% (Ti + Al), 2.8wt% Nb).

  7. Innovative technologies for powder metallurgy-based disk superalloys: Progress and proposal

    Science.gov (United States)

    Chong-Lin, Jia; Chang-Chun, Ge; Qing-Zhi, Yan

    2016-02-01

    Powder metallurgy (PM) superalloys are an important class of high temperature structural materials, key to the rotating components of aero engines. In the purview of the present challenges associated with PM superalloys, two novel approaches namely, powder preparation and the innovative spray-forming technique (for making turbine disk) are proposed and studied. Subsequently, advanced technologies like electrode-induction-melting gas atomization (EIGA), and spark-plasma discharge spheroidization (SPDS) are introduced, for ceramic-free superalloy powders. Presently, new processing routes are sought after for preparing finer and cleaner raw powders for disk superalloys. The progress of research in spray-formed PM superalloys is first summarized in detail. The spray-formed superalloy disks specifically exhibit excellent mechanical properties. This paper reviews the recent progress in innovative technologies for PM superalloys, with an emphasis on new ideas and approaches, central to the innovation driving techniques like powder processing and spray forming. Project supported by the National Natural Science Foundation of China (Grant Nos. 50974016 and 50071014).

  8. Hot deformation behavior of delta-processed superalloy 718

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y., E-mail: wangyanhit@yahoo.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); School of Aeronautics and Astronautics, Central South University, Changsha 410083 (China); Shao, W.Z.; Zhen, L.; Zhang, B.Y. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2011-03-25

    Research highlights: {yields} The peak stress for hot deformation can be described by the Z parameter. {yields} The grain size of DRX was inversely proportional to the Z parameter. {yields} The dissolution of {delta} phases was greatly accelerated under hot deformation. {yields}The {delta} phase stimulated nucleation can serve as the main DRX mechanism. - Abstract: Flow stress behavior and microstructures during hot compression of delta-processed superalloy 718 at temperatures from 950 to 1100 deg. C with strain rates of 10{sup -3} to 1 s{sup -1} were investigated by optical microscopy (OM), electron backscatter diffraction (EBSD) technique and transmission electron microscopy (TEM). The relationship between the peak stress and the deformation conditions can be expressed by a hyperbolic-sine type equation. The activation energy for the delta-processed superalloy 718 is determined to be 467 kJ/mol. The change of the dominant deformation mechanisms leads to the decrease of stress exponent and the increase of activation energy with increasing temperature. The dynamically recrystallized grain size is inversely proportional to the Zener-Hollomon (Z) parameter. It is found that the dissolution rate of {delta} phases under hot deformation conditions is much faster than that under static conditions. Dislocation, vacancy and curvature play important roles in the dissolution of {delta} phases. The main nucleation mechanisms of dynamic recrystallization (DRX) for the delta-processed superalloy 718 include the bulging of original grain boundaries and the {delta} phase stimulated DRX nucleation, which is closely related to the dissolution behavior of {delta} phases under certain deformation conditions.

  9. Pulsed laser-assisted machining of Inconel 718 superalloy

    Science.gov (United States)

    Azhdari Tadavani, Soheila; Shoja Razavi, Reza; Vafaei, Reza

    2017-01-01

    Nickel-based superalloys including Inconel 718(IN718) are widely used in aerospace industries due to their superior high temperature strength, toughness, and corrosion resistance. These alloys are difficult to machine mainly because of their low thermal conductivity and high work hardening rate, which cause steep temperature gradient and high cutting forces at the tool edge. The application of laser assisted machining is the subject of many new researches since shear forces; surface coarsening and tool wear are reduced. The aim of this investigation was to evaluate laser assisted machining behavior of a 718 Inconel superalloy from the view point of machining specific energy, surface roughness, tool wear and chip appearance. Experimental apparatuses used included optical and scanning electron microscopy, spark emission spectroscopy, and EDS analysis. The results indicated that increasing the temperature to about 540 °C just ahead of primary shear zone, can result in 35% reduction of machining specific energy, in comparison with conventional machining. Furthermore, surface coarsening and tool wear were reduced by 22% and 23% respectively. Flank wear was the main deteriorating factor on cutting tools during laser assisted machining. SEM micrographs indicated that increase in temperature has no noticeable effect on finished workpiece surface. Analysis of variance obtained from regression analysis indicated that frequency of laser beam has the most influential effect on temperature. The optimum conditions for laser assisted machining of 718 superalloy is suggested as follows: 80 Hz frequency, 400 W power, 24 m/min cutting speed, and 0.052 mm/rev feed rate along with 540 °C temperature, 2.51 J/mm2 machining specific energy and 130 N cutting force.

  10. Progress on modeling and simulation of directional solidification of superalloy turbine blade casting

    Directory of Open Access Journals (Sweden)

    Xu Qingyan

    2012-02-01

    Full Text Available Directional solidified turbine blades of Ni-based superalloy are widely used as key parts of the gas turbine engines. The mechanical properties of the blade are greatly influenced by the final microstructure and the grain orientation determined directly by the grain selector geometry of the casting. In this paper, mathematical models were proposed for three dimensional simulation of the grain growth and microstructure evolution in directional solidification of turbine blade casting. Ray-tracing method was applied to calculate the temperature variation of the blade. Based on the thermo model of heat transfer, the competitive grain growth within the starter block and the spiral of the grain selector, the grain growth in the blade and the microstructure evolution were simulated via a modified Cellular Automaton method. Validation experiments were carried out, and the measured results were compared quantitatively with the predicted results. The simulated cooling curves and microstructures corresponded well with the experimental results. The proposed models could be used to predict the grain morphology and the competitive grain evolution during directional solidification.

  11. Microstructure and Creep Property of a GH4169 Nickel-based Superalloy

    Directory of Open Access Journals (Sweden)

    LIU Chen

    2017-06-01

    Full Text Available By means of direct aging (DA heat treatment, creep properties measurement and microstructure observation, the microstructure and creep behaviors of the GH4169 superalloy were investigated. Results show that the microstructure of the alloy consists of γ, γ', γ" and δ phases, and the coherent interfaces exist between the phases. The creep life of the alloy at 660℃/700 MPa is predicted to be 123h, and 39h at 680℃/700MPa. Under the testing temperature and stress range, the creep activation energy of the alloy is calculated to be 588.0 kJ/mol. The deformation mechanisms of the alloy during creep are dislocation slipping and twin deformation. The granular carbides precipitated along the grain boundaries may restrain the slipping of the boundary, which is thought to be the main reason of the good creep resistance. As the creep goes on, the slipping dislocations activated within the grains are hindered and blocked by the boundaries to cause the stress concentration, which may promote the initiation and propagation of the crack occurring along the boundaries perpendicular to the stress axis, when the value of stress concentration is higher than the bonding strength of the boundaries, up to the occurrence of creep fracture. This is thought to be the fracture mechanism of alloy during creep.

  12. Fatigue Behavior and Deformation Mechanisms in Inconel 718 Superalloy Investigated

    Science.gov (United States)

    2005-01-01

    The nickel-base superalloy Inconel 718 (IN 718) is used as a structural material for a variety of components in the space shuttle main engine (SSME) and accounts for more than half of the total weight of this engine. IN 718 is the bill-of-material for the pressure vessels of nickel-hydrogen batteries for the space station. In the case of the space shuttle main engine, structural components are typically subjected to startup and shutdown load transients and occasional overloads in addition to high-frequency vibratory loads from routine operation. The nickel-hydrogen battery cells are prooftested before service and are subjected to fluctuating pressure loads during operation. In both of these applications, the structural material is subjected to a monotonic load initially, which is subsequently followed by fatigue. To assess the life of these structural components, it is necessary to determine the influence of a prior monotonic load on the subsequent fatigue life of the superalloy. An insight into the underlying deformation and damage mechanisms is also required to properly account for the interaction between the prior monotonic load and the subsequent fatigue loading. An experimental investigation was conducted to establish the effect of prior monotonic straining on the subsequent fatigue behavior of wrought, double-aged, IN 718 at room temperature. First, monotonic strain tests and fully-reversed, strain-controlled fatigue tests were conducted on uniform-gage-section IN 718 specimens. Next, fully reversed fatigue tests were conducted under strain control on specimens that were monotonically strained in tension. Results from this investigation indicated that prior monotonic straining reduced the fatigue resistance of the superalloy particularly at the lowest strain range. Some of the tested specimens were sectioned and examined by transmission electron microscopy to reveal typical microstructures as well as the active deformation and damage mechanisms under each of

  13. MICROSTRUCTURE AND MECHANICAL PROPERTIES OF NOVEL 718 SUPERALLOY

    Institute of Scientific and Technical Information of China (English)

    J.H. Du; X.D. Lü; J.L. Qu; Q. Deng; J.Y. Zhuang; Z.Y. Zhong

    2006-01-01

    Recently, a novel 718 superalloy with remarkable structural stability at 680℃ has been designed and fabricated by CISRI (Central Iron and Steel Research Institute) etc. Phase identification of novel 718 alloy under the above-mentioned heat-treatment condition was performed using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Results show that the novel 718 alloy has outstanding structural stability at 680℃. The novel 718alloy possess excellent structural stability and good mechanical properties, which is attributed to y-phase strengthening and also to the specific sandwich structure of the γ′ + γ" strengthening phase.

  14. Zitongxi Block

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    @@ Zitongxi Block (Western Zitong Block), is located in Zitong County, northwest of Sichuan Province (as shown on Fig. 8 ). Geologically. it is situated in the Zitong Depression, southwest of the middle Longmenshan faulted and folded belt, covering an area of 1 830 km2. Transportation is very convenient. A crisscross network of highways run through the block and the Baocheng railway is nearby. The climate is moderate. Most area belongs to hilly land with the elevation of 500-600 m.The Tongjiang River runs across the area.

  15. Digital image encryption with chaotic map lattices

    Institute of Scientific and Technical Information of China (English)

    Sun Fu-Yan; Lü Zong-Wang

    2011-01-01

    This paper proposes a secure approach for encryption and decryption of digital images with chaotic map lattices.In the proposed encryption process, eight different types of operations are used to encrypt the pixels of an image and one of them will be used for particular pixels decided by the outcome of the chaotic map lattices. To make the cipher more robust against any attacks, the secret key is modified after encrypting each block of sixteen pixels of the image.The experimental results and security analysis show that the proposed image encryption scheme achieves high security and efficiency.

  16. Effect of alloying by lanthanum and high rhenium superalloys on the basis of Ni-Al-Cr on the structure and phase composition

    Energy Technology Data Exchange (ETDEWEB)

    Kozlov, Eduard, E-mail: kozlov@tsuab.ru; Tsedrik, Elena, E-mail: tsedrik@sibmail.ru; Koneva, Nina, E-mail: koneva@tsuab.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Popova, Natalya, E-mail: natalya-popova-44@mail.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Institute of Strength Physics and Materials Science, SB RAS, 2/4, Academicheskii Av., 634055, Tomsk (Russian Federation); Nikonenko, Elena, E-mail: vilatomsk@mail.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 30, Lenin Av., 634050, Tomsk (Russian Federation); Fedoricheva, Marina, E-mail: fed-mv@mail.ru [Institute of Strength Physics and Materials Science, SB RAS, 2/4, Academicheskii Av., 634055, Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 30, Lenin Av., 634050, Tomsk (Russian Federation)

    2016-01-15

    This paper presents transmission and scanning electronic microscope investigations of Ni-Al-Cr superalloy alloyed with additional Re and La elements. This superalloy is obtained by the directional solidification method and subsequently is subjected to two-stage high-temperature annealing: 1) at T = 1150°C, the test time is 1 hour; 2) at T = 1100°C, the testing time is 1430 hours. It was found that the γ- and γ′-phases are the main phases in the two states on the basis of fcc lattice. Where γ is the disordered fcc solid solution and γ′-phase is the main phase with an ordered arrangement of atoms having the L1{sub 2} superstructure. It is shown that such additional elements as Re and La result in the formation of new phases in Ni-Al-Cr accompanied by considerable modifications of quasi-cuboid structure in its γ′-phase. The phase composition and morphology of the phases are studied.

  17. Perfect Actions and Operators for Lattice QCD

    Science.gov (United States)

    Wiese, Uwe-Jens

    1996-05-01

    Wilson's renormalization group implies that lattice actions located on a renormalized trajectory emanating from a fixed point represent perfect discretizations of continuum physics. With a perfect action the spectrum of a lattice theory is identical with the one of the continuum theory even at finite lattice spacing. Similarly, perfect operators yield cut-off independent matrix elements. Hence, continuum QCD can in principle be reconstructed from a lattice with finite spacing. In practice it is difficult to construct perfect actions and perfect operators explicitly. Here perturbation theory is used to derive perfect actions for quarks and gluons by performing a block renormalization group transformation directly from the continuum. The renormalized trajectory for free massive quarks is identified and a parameter in the renormalization group transformation is tuned such that for 1-d configurations the perfect action reduces to the nearest neighbor Wilson fermion action. Then the 4-d perfect action turns out to be extremely local as well, which is vital for numerical simulations. The fixed point action for free gluons is also obtained by blocking from the continuum. For 2-d configurations it reduces to the standard plaquette action, and for 4-d configurations it is still very local. With interactions between quarks and gluons switched on the perfect quark-gluon and 3-gluon vertex functions are computed analytically. In particular, a perfect clover term can be extracted from the quark-gluon vertex. The perturbatively perfect action is directly applicable to heavy quark physics. The construction of a perfect QCD action for light quarks should include nonperturbative effects, which is possible using numerical methods. Classically perfect quark and gluon fields are constructed as well. They allow to interpolate the continuum fields from the lattice data. In this way one can obtain information about space-time regions between lattice points. The classically perfect fields

  18. Chengzikou Block

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    @@ Chengzikou Block is located in the north of Hekou district, Dongying City, Shandong Province, adjacent to Bohai Bay. It can be geographically divided into three units: onshore, transitional zone and offshore ultrashallow zone, totally covering an area of 470 km2. The southern onshore area is low and gentle in topography;the northern shallow sea is at water depths of 2-8 m below sea level, and the transitional zone occupies more than 60% of the whole block. The climate belongs to temperate zone with seasonal wind. Highways are welldeveloped here, and the traffic is very convenient. The Chengzikou Block is about 80 km away from Dongying City and 290 km from Jinan City in the south. The northern offshore area of the block is 160 km away from Longkou port in the east and only 38 km away in the west from Zhuangxi port.

  19. Longmenshan Block

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    @@ Longmenshan Block is located in Jiange County of Jiangyou City in the northwest of Sichuan Basin. covering an area of 2 628 km2. Geologically, it is situated in the Mid-Longmenshan fault and fold belt, neighbouring Zitong Depression in its southeast. There are mountains surrounding its northwest , the rest area being hilly land,with the elevation of 500-700 m. The BaoCheng railway and the No. 108 highway run through the block, the traffic is very convenient.

  20. Effect of Zr addition on precipitates in K4169 superalloy

    Directory of Open Access Journals (Sweden)

    Liu Jie

    2012-02-01

    Full Text Available In order to investigate the effect of Zr addition on the precipitations of K4169 superalloy, a manual electric arc furnace was used to prepare the superalloy with different Zr addition from 0.03wt.% to 0.07wt%. After standard heat treatment and long-time aging, the microstructures of the alloys were observed using XRD, SEM and TEM. The results show that Zr not only inhibits the precipitation of Laves phase at the grain boundary, but also significantly promotes the precipitation of earlobe-like γ′and γ″ phases. After long time aging at 680 ℃ for 500 h, the γ″phase grows up obviously and forms a γ′/γ′′clad microstructure when the Zr addition is 0.03 wt.%. A large number of fine orbed γ′particles precipitate in the grains and some γ″phase transforms to disk-like δ phase when the Zr addition increases to 0.05wt.%. The nano-polycrystalline γ′phase precipitates in the grains and there is a little δ phase when the Zr addition is 0.07wt.%. As the Zr addition increases, the amount of Laves phase at the grain boundary decreases at first, and then increases and forms flaky morphology.

  1. Recrystallization of Single Crystal Nickel-Based Superalloy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bing; TAO Chun-hu; LU Xin; LIU Chang-kui; HU Chun-yan; BAI Ming-yuan

    2009-01-01

    A series of experiments of investigating the recrystallization of single crystal DD3 superalloy were carried out. The threshold temperature for recrystallization and the effect of annealing temperature on recrystaUization were studied. The results show that the threshold temperature for recrystallization of the shot-peened DD3 samples is be-tween 1 000 ℃ and 1 050℃ under the condition of annealing for 2 h, and the recrystallization depth increases with the rise of the annealing temperature. Below 1 150 ℃, the recrystallization depth increases slowly with the tempera-ture climbing, while above 1 150 ℃, the recrystallization depth increases quickly with the rise of the temperature. The solution of the γ' phase is a critical factor of the recrystallization behavior of DD3 superalloy. In addition, the ki-netics and microstructural evolution of recrystallization at 1 200 ℃ were also studied. It is found that the recrystalli-zation progresses rapidly at 1 200℃ through the growth of fully developed recrystallized grains, and the recrystalli-zation process on the shot-peened surface is similar to that of wrought materials, including nucleation of reerystalliza-tion, growth of new grains into the matrix, and growth of new grains by swallowing up each other.

  2. Jammed lattice sphere packings

    OpenAIRE

    Kallus, Yoav; Marcotte, Étienne; Torquato, Salvatore

    2013-01-01

    We generate and study an ensemble of isostatic jammed hard-sphere lattices. These lattices are obtained by compression of a periodic system with an adaptive unit cell containing a single sphere until the point of mechanical stability. We present detailed numerical data about the densities, pair correlations, force distributions, and structure factors of such lattices. We show that this model retains many of the crucial structural features of the classical hard-sphere model and propose it as a...

  3. On Traveling Waves in Lattices: The Case of Riccati Lattices

    Science.gov (United States)

    Dimitrova, Zlatinka

    2012-09-01

    The method of simplest equation is applied for analysis of a class of lattices described by differential-difference equations that admit traveling-wave solutions constructed on the basis of the solution of the Riccati equation. We denote such lattices as Riccati lattices. We search for Riccati lattices within two classes of lattices: generalized Lotka-Volterra lattices and generalized Holling lattices. We show that from the class of generalized Lotka-Volterra lattices only the Wadati lattice belongs to the class of Riccati lattices. Opposite to this many lattices from the Holling class are Riccati lattices. We construct exact traveling wave solutions on the basis of the solution of Riccati equation for three members of the class of generalized Holling lattices.

  4. Twisted mass lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Shindler, A. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

    2007-07-15

    I review the theoretical foundations, properties as well as the simulation results obtained so far of a variant of the Wilson lattice QCD formulation: Wilson twisted mass lattice QCD. Emphasis is put on the discretization errors and on the effects of these discretization errors on the phase structure for Wilson-like fermions in the chiral limit. The possibility to use in lattice simulations different lattice actions for sea and valence quarks to ease the renormalization patterns of phenomenologically relevant local operators, is also discussed. (orig.)

  5. Microstructural studies of carbides in MAR-M247 nickel-based superalloy

    Science.gov (United States)

    Szczotok, A.; Rodak, K.

    2012-05-01

    Carbides play an important role in the strengthening of microstructures of nickel-based superalloys. Grain boundary carbides prevent or retard grain-boundary sliding and make the grain boundary stronger. Carbides can also tie up certain elements that would otherwise promote phase instability during service. Various types of carbides are possible in the microstructure of nickel-based superalloys, depending on the superalloy composition and processing. In this paper, scanning electron and scanning transmission electron microscopy studies of carbides occurring in the microstructure of polycrystalline MAR-M247 nickel-based superalloy were carried out. In the present work, MC and M23C6 carbides in the MAR-M247 microstructure were examined.

  6. High temperature cyclic oxidation and hot corrosion behaviours of superalloys at 900°C

    Indian Academy of Sciences (India)

    Subhash Kamal; R Jayaganthan; S Prakash

    2010-06-01

    Oxidation and hot corrosion are serious problems in aircraft, marine, industrial, and land-base gas turbines. It is because of the usage of wide range of fuels coupled with increased operating temperatures, which leads to the degradation of turbine engines. To obviate these problems, superalloys, viz. Superni 75, Superni 718 and Superfer 800H superalloys (Midhani grade), are the prominent materials for the high temperature applications. It is very essential to investigate the degradation mechanism of superalloys due to oxidation and hot corrosion and substantiate the role of alloying elements for the formation of protective oxide films over the surface of the superalloys. Therefore, the present work investigates the oxidation and hot corrosion behaviour of superalloys exposed to air and molten salt (Na2SO4–60% V2O5) environment, respectively, at 900°C under cyclic conditions. The weight change measurements made on the superalloys during the experiments are used to determine the kinetics of oxidation and hot corrosion. X-ray diffraction (XRD), X-ray mapping and field emission scanning electron microscope (FESEM, FEI, Quanta 200F company) with EDAX Genesis software attachment, made in Czech Republic are used to characterize the corroded products of the superalloys. It is observed that the formation of scale rich in Cr2O3, NiO and spinel NiCr2O4 has contributed for the better oxidation and hot corrosion resistance of Superni 75; whereas relatively lesser hot corrosion resistance of Superfer 800H is due to the formation of non-protective oxides of iron and sulphides of iron and nickel. The parabolic rate constants calculated for the superalloys show that the corrosion rate is minimum in air as compared to molten salt environment.

  7. Additional thermal fatigue data on nickel- and cobalt-base superalloys, part 1

    Science.gov (United States)

    Howes, M. A. H.

    1973-01-01

    The fluidized bed technique was used to measure the relative thermal fatigue resistance of twenty-one superalloys. Among the thirty-six variations of composition, solidification method, and surface protection the cycles to cracking differed by two to three orders of magnitude. Some alloys suffered serious weight losses and oxidation. Thermal fatigue data, oxidation, and dimensional changes are reported. The types of superalloys are identified.

  8. Superalloys 1984; Proceedings of the Fifth International Symposium, Champion, PA, October 7-11, 1984

    Energy Technology Data Exchange (ETDEWEB)

    Radavich, J.F.; Gell, M.; Kortovich, C.S.; Bricknell, R.H.; Kent, W.B.

    1984-01-01

    The papers presented in this volume provide an overview of original research, development, and applications work on iron, cobalt, and nickel superalloys intended for elevated temperature usage. Topics discussed include polycrystalline castings and properties; directionally solidified and single crystal alloys and properties; powder processing, properties, and products; and advances in processing. The discussion also covers new alloys and alloying effects as well as the environmental behavior of superalloys and fracture mechanics.

  9. A Method of Stray Grain Suppression for Single-Crystal Superalloy During Seed Melt-Back

    Science.gov (United States)

    Xuan, Weidong; Lan, Jian; Liu, Huan; Li, Chuanjun; Zhong, Yunbo; Ren, Xingfu; Li, Xi; Cao, Guanghui; Ren, Zhongming

    2016-12-01

    The suppression of stray grains during seed melt-back of single-crystal superalloy through thermal resistance technique has been investigated based on both experimental observations and numerical simulation. The results indicate that the introduction of thermal resistance layer significantly suppresses the stray grain formation of single-crystal superalloy. Based on both theoretical analysis and numerical simulation, above results should be attributed to the decrease of radial heat transfer of sample in the thermal resistance layer.

  10. Gamma Prime Morphology and Creep Properties of Nickel Based Superalloys With Platinum Group Metal Additions (Preprint)

    Science.gov (United States)

    2008-04-01

    creep resistance. Polycrystalline superalloy MAR - M247 can sustain a creep rate of 10-8 s-1 at 982°C at a stress of 172 MPa [44], while the alloys...Nathal, R.D. Maier, and L.J. Ebert, “The Influence of Cobalt on the Tensile and Stress Rupture Properties of the Nickel-Base Superalloy MAR - M247 ,” Metallurgical Transactions A, 13 (A) (1982), 1767-1774.           10

  11. Chadong Block

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    @@ The Chadong Block, located in the east of Qaidam Basin, Qinghai Province, covers an area of 12 452 km2. It is bounded by Kunlum Mountains in the south and the northwest is closely adjacent to Aimunike Mountain.Rivers are widely distributed, which always run in NWSE direction, including the Sulunguole, Qaidam and Haluwusu Rivers. The traffic condition is good, the Qinghai-Tibet highway stretching through the whole area and the Lan-Qing railway, 20-50 km away from the block, passing from north to west. A lot of Mongolia minority people have settled there, of which herdsmen always live nearby the Qaidam River drainage area.

  12. THE ROLE OF NIOBIUM IN NICKEL-BASED SUPERALLOYS AND CHARACTERIZATION OF PM ALLOY EP741NP

    Institute of Scientific and Technical Information of China (English)

    T. Carneiro; J. Radavich; D. Furrer

    2005-01-01

    The role of niobium in nickel-based superalloys is reviewed. The importance of niobium as a strengthener is discussed. New developments in nickel-based superalloys are also briefly mentioned, including some results that show improved resistance to sulfidation by niobium. Research results from a current program on the role of niobium in the Russian powder metallurgy alloy EP741NP are presented. Future research plans on the role of niobium in superalloys are also discussed.

  13. A Coupled Creep-Plasticity Model for Residual Stress Relaxation of a Shot-Peened Nickel-Base Superalloy

    Science.gov (United States)

    2007-05-01

    Superalloys for Turbine Discs ,” Journal of the Minerals, Metals & Materials Society (JOM), January 1999, pp. 14-17. 48. Fecht, H., and Furrer, D...Processing of Nickel-Base Superalloys for Turbine Engine Disc Applications,” Advanced Engineering Materials, Vol. 2, No. 12, 2000, pp. 777-787. 49...and McLean, M. “Tension-Compression creep asymmetry in a turbine disc superalloy : roles of internal stress and thermal ageing,” Acta Materialia, 52

  14. A Coupled Creep Plasticity Model for Residual Stress Relaxation of a Shot Peened Nickel-Base Superalloy (Postprint)

    Science.gov (United States)

    2008-09-01

    McLean, M. “Tension- Compression creep asymmetry in a turbine disc superalloy : roles of internal stress and thermal ageing,” Acta Materialia, 52, 2004...AFRL-RX-WP-TP-2009-4156 A COUPLED CREEP PLASTICITY MODEL FOR RESIDUAL STRESS RELAXATION OF A SHOT PEENED NICKEL-BASE SUPERALLOY (POSTPRINT...SUBTITLE A COUPLED CREEP PLASTICITY MODEL FOR RESIDUAL STRESS RELAXATION OF A SHOT PEENED NICKEL-BASE SUPERALLOY (POSTPRINT) 5a. CONTRACT NUMBER

  15. Characterization of oxide scales to evaluate high temperature oxidation behavior of Ni-20Cr coated superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Singh, H. [Mechanical Engineering Department, BBSB Engineering College, Fatehgarh Sahib 140407 (India)], E-mail: hnr97@yahoo.com; Puri, D.; Prakash, S. [Metallurgical and Materials Engineering Department, Indian Institute of Technology Roorkee, Roorkee 247 667 (India); Maiti, Rabindranath [Central Research Facilities, Indian Institute of Technology Kharaghpur, Kharaghpur (India)

    2007-08-25

    Modern thermal spray processes such as plasma spraying are usually considered to deposit high-chromium, nickel-chromium coatings onto the superalloys to enhance their high temperature oxidation resistance. The purpose of these coatings is to form long-lasting oxidation protective scales. In the current investigation, Ni-20Cr alloy powder was deposited on three Ni-base superalloys; Superni 75, Superni 600 and Superni 601 by shrouded plasma spray process. Oxidation kinetics was established for the uncoated as well as the coated superalloys in air at 900 deg. C under cyclic conditions for 50 cycles by thermogravimetric technique. Each cycle consisted of 1 h heating followed by 20 min of cooling in air. All the coated superalloys nearly followed the parabolic rate law of oxidation. X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray (SEM/EDAX) techniques were used to characterise the oxide scales. The coating was found to be successful in maintaining its integrity with the superalloy substrates in all the cases. The oxide scales formed on the oxidized coated superalloys were found to be intact and spallation-free in general. The XRD analysis revealed the presence of phase like NiO, Cr{sub 2}O{sub 3} and NiCr{sub 2}O{sub 4} in the oxide scales. The XRD results were further supported by the SEM/EDAX analyses.

  16. Nuclear lattice simulations

    Directory of Open Access Journals (Sweden)

    Epelbaum E.

    2010-04-01

    Full Text Available We review recent progress on nuclear lattice simulations using chiral effective field theory. We discuss lattice results for dilute neutron matter at next-to-leading order, three-body forces at next-to-next-toleading order, isospin-breaking and Coulomb effects, and the binding energy of light nuclei.

  17. Simulation of oxidation-nitridation-induced microstructural degradation in a cracked Ni-based superalloy at high temperature

    Directory of Open Access Journals (Sweden)

    Yuan Kang

    2014-01-01

    Full Text Available In turbine engines, high temperature components made of superalloys may crack in a creep process during service. With the inward flux of the gases, e.g. oxygen and nitrogen, along those cracks, the microstructure of the superalloy substrate nearby the cracks may degrade by internal oxidation and nitridation. The aim of this study is to investigate and simulate the oxidation-nitridation-induced microstructural degradation in superalloys by taking a variant of Ni-based superalloy IN-792 as a sample. After the creep testing of the superalloy in air, the microstructures on the cross section of the superalloy were analysed in a scanning electron microscope, equipped with energy/wavelength dispersive systems. Internal oxidation and nitridation, presenting by Al/Ti oxides and nitrides, were observed under a porous and even cracked Cr-oxide scale which was formed on the superalloy surface or along the creep cracks connecting the superalloy surface. Meanwhile, the reinforcing γ′ precipitates were depleted. Such oxidation-nitridation-induced microstructural degradation was simulated by using an oxidation-diffusion model, focusing the diffusion of the alloying elements in metallic phases of the superalloy.

  18. Oxidation and emittance of superalloys in heat shield applications

    Science.gov (United States)

    Wiedemann, K. E.; Clark, R. K.; Unnam, J.

    1986-01-01

    Recently developed superalloys that form alumina coatings have a high potential for heat shield applications for advanced aerospace vehicles at temperatures above 1095C. Both INCOLOY alloy MA 956 (of the Inco Alloys International, Inc.), an iron-base oxide-dispersion-strengthened alloy, and CABOT alloy No. 214 (of the Cabot Corporation), an alumina-forming nickel-chromium alloy, have good oxidation resistance and good elevated temperature strength. The oxidation resistance of both alloys has been attributed to the formation of a thin alumina layer (alpha-Al2O3) at the surface. Emittance and oxidation data were obtained for simulated Space Shuttle reentry conditions using a hypersonic arc-heated wind tunnel. The surface oxides and substrate alloys were characterized using X-ray diffraction and scanning and transmission electron microscopy with an energy-dispersive X-ray analysis unit. The mass loss and emittance characteristics of the two alloys are discussed.

  19. Laser engineered net shaping of Co-based superalloys

    Institute of Scientific and Technical Information of China (English)

    XUE Chun-fang; DAI Yao; TIAN Xin-li

    2006-01-01

    Laser engineered net shaping(LENS) process was investigated using Co-based superalloy powder with a high power continuous wave CO2 laser. Thin wall part with smooth surface was obtained by LENS of layer-by-layer deposition of the powder materials. This thin wall sample was tested for metallographic examinations, micro-hardness, X-ray diffraction and mechanical property test. Microstructural results show that the layers possess rapid solidification microstructural feature, fine dendritic crystal and M7C3-type carbides (essentially chromium-rich carbide) dispersed in the γ(Co,Cr) phase matrix. Dendrite spacing as well as the solidification mode can be controlled through control process parameters. In addition, this microstructural feature of the as-formed Co-base sample leads to an evident hardening and a superior tensile strength and toughness.

  20. Phase transformations and microstructure of IN-713C nickel superalloy

    Directory of Open Access Journals (Sweden)

    F. Binczyk

    2009-04-01

    Full Text Available The study presents the results of investigations of phase transformations taking place during melting and solidification and ofmicrostructural examinations carried out on the family of IN 713C nickel superalloys. Examinations were carried out by the method ofthermal analysis (ATD and differential scanning calorimetry (DSC. It has been concluded that the method of thermal analysis (ATDenables more precise assessment of the precipitation of the primary phases of a low value of the solidification enthalpy. The advantage ofDSC is the possibility of determination of the value of the heat (enthalpy of phase transformations during alloy melting and solidification. The measured parameters of Tlik and Tsol are comparable for both methods. Microstructural examinations have confirmed the phenomena accompanying phase transformations, i.e. the precipitation of primary carbides, the solidification of y' phase matrix and carbide eutectic, and the formation of y’ phase in solid state.

  1. N18, powder metallurgy superalloy for disks: Development and applications

    Energy Technology Data Exchange (ETDEWEB)

    Guedou, J.Y.; Lautridou, J.C.; Honnorat, Y. (SNECMA, Evry (France). Materials and Processes Dept.)

    1993-08-01

    The preliminary industrial development of a powder metallurgy (PM) superalloy, designated N18, for disk applications has been completed. This alloy exhibits good overall mechanical properties after appropriate processing of the material. These properties have been measured on both isothermally forged and extruded billets, as well as on specimens cut from actual parts. The temperature capability of the alloy is about 700 C for long-term applications and approximately 750 C for short-term use because of microstructural instability. Further improvements in creep and crack propagation properties, without significant reduction in tensile strength, are possible through appropriate thermomechanical processing, which results in a large controlled grain size. Spin pit tests on subscale disks have confirmed that the N18 alloy has a higher resistance than PM Astrology and is therefore an excellent alloy for modern turbine disk applications.

  2. The characteristics of serrated flow in superalloy IN738LC

    Energy Technology Data Exchange (ETDEWEB)

    Sharghi-Moshtaghin, Reza [Department of Materials Science and Engineering, Sharif University of Technology, Azadi Avenue, Tehran (Iran, Islamic Republic of); Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, OH 44106 (United States)], E-mail: rxs270@case.edu; Asgari, Sirous [Department of Materials Science and Engineering, Sharif University of Technology, Azadi Avenue, Tehran (Iran, Islamic Republic of)

    2008-07-15

    Serrated flow was investigated in superalloy IN738LC, a nickel-base {gamma}' age-hardened alloy. In this material serrated flow appeared between 350 and 450 deg. C and strain rate of (8.77 x 10{sup -5} to 8.77 x 10{sup -3}) s{sup -1}. Activation energy for this process was calculated to be 0.69-0.86 eV which is in good agreement with the values reported for similar alloys. Results show that the diffusion rate of substitutional solute atoms at this temperature range is too low to cause this effect. This suggests that the interaction of solute atoms and moving dislocation is responsible for the observed serrated flow in this alloy.

  3. Supersolidus Liquid Phase Sintering Modeling of Inconel 718 Superalloy

    Science.gov (United States)

    Levasseur, David; Brochu, Mathieu

    2016-02-01

    Powder metallurgy of Inconel 718 superalloy is advantageous as a near-net shape process for complex parts to reduce the buy-to-fly ratio and machining cost. However, sintering Inconel 718 requires the assistance of supersolidus liquid formation to achieve near full density and involves the risk of distortion at high temperatures. The present work is focused on modeling the onset of sintering and distortion as a function of temperature, grain size, and part geometry for Inconel 718. Using experimental sintering results and data available in the literature, the supersolidus liquid phase sintering of Inconel 718 was modeled. The model was used to define a processing window where part distortion would be avoided.

  4. Macro- and microhardness of IN-713C nickel superalloy constituents

    Directory of Open Access Journals (Sweden)

    F. Binczyk

    2009-10-01

    Full Text Available The results of investigations of the effect of modification and cooling rate on the macrohardness of castings and microhardness of phase constituents in IN-713C nickel superalloy were described. As an inoculant, cobalt aluminate CoAl2O4 in composition with aluminium powder and colloidal silica was used. Changes in the cooling rate were obtained using a cast stepped test piece with steps of 6, 11 and 17 mm thickness. Macrohardness of the cast test piece steps was measured by Brinell technique, while Vickers method was used to measure the microhardness of γ and γ’ phases present in the alloy matrix, as well as the hardness of eutectic carbide precipitates.A significant effect of the cooling rate and modification treatment on the results of the measurements was stated, and difficulties in performing correctly the microhardness measurements due to the precipitates dimensions, especially after the modification treatment, were highlighted.

  5. Creep curve modelling of a conventionally cast nickel base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Lupinc, V.; Maldini, M. [CNR - IENI, Milan (Italy); Poggio, E.; Vacchieri, E. [Ansaldo Energia S.p.A., Genoa (Italy)

    2010-07-01

    Constant load creep tests on Rene 80, a nickel base superalloy for gas turbine blade application, were run in the temperature interval 800-950 C with applied stresses producing rupture times up to 1000 h. Creep curves are generally dominated by a long accelerating/tertiary creep that follows a relatively small decelerating/primary creep. No steady state stage has been observed. Analysis of the creep curves has shown that a single damage parameter can describe the long accelerating/tertiary state in the explored temperature range. The damage appears to be dependent on the accumulated creep strain and, as a first approximation, independent on the applied stress and temperature. The whole creep curve, primary and tertiary stages, has been modelled by a simple set of coupled differential equations obtained using the formalism of the Continuum Damage Mechanics. The proposed set of equations has an analytical solution, strain vs. time, for creep curves at constant temperature and stress. (orig.)

  6. STABILITY ANALYSIS OF RADIAL TURNING PROCESS FOR SUPERALLOYS

    Directory of Open Access Journals (Sweden)

    Alberto JIMÉNEZ

    2017-07-01

    Full Text Available Stability detection in machining processes is an essential component for the design of efficient machining processes. Automatic methods are able to determine when instability is happening and prevent possible machine failures. In this work a variety of methods are proposed for detecting stability anomalies based on the measured forces in the radial turning process of superalloys. Two different methods are proposed to determine instabilities. Each one is tested on real data obtained in the machining of Waspalloy, Haynes 282 and Inconel 718. Experimental data, in both Conventional and High Pressure Coolant (HPC environments, are set in four different states depending on materials grain size and Hard-ness (LGA, LGS, SGA and SGS. Results reveal that PCA method is useful for visualization of the process and detection of anomalies in online processes.

  7. SUPERPLASTICITY AND DIFFUSION BONDING OF IN718 SUPERALLOY

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The superplasticity and diffusion bonding of IN718 superalloy were studied in this article. The strain rate sensitivity index m was obtained at different temperatures and various initial strain rates using the tensile speed mutation method; m reached its maximum value 0.53 at an initial strain rate of 1 ×10-4s-1 at 1253K. The diffusion bonding parameters, including the bonding temperature T,pressure p, and time t, affected the mechanism of joints. When the bonded specimen with 25μm thick nickel foil interlayer was tensile at room temperature, the shear fracture of the joints with nickel foil interlayer took place at the IN718 part. Microstructure study was carried out with the bonded samples. The microstructure shows an excellent bonding at the interfaces. The optimum parameters for the diffusion bonding are: T= 1273-1323K, p = 20-30MPa, t = 45-60min.

  8. Tensile Strain Hardening Behavior and Fractography of Superalloy GH39

    Directory of Open Access Journals (Sweden)

    WANG Hui

    2016-10-01

    Full Text Available The strain hardening behaviour and fractography of superalloy GH39 was investigated by tensile test at different strain rates. Results indicate that strain hardening behaviours are different during the deformation process. True stress-strain curve obeys the Hollomon relationship partly. The strain hardening exponentn in this stage is constant in the initial plastic stage. However, the value of n increased with true strain ε increasing when true strain is between 0.014 and 0.13. A lot of deformation twinning can be found, the twins and dislocations worked together to increase the value of n. The strain hardening exponent is increased lightly with the strain rate increasing, SEM observations show that in the case of low strain rate, the fracture mode is typical ductile, but there is a tendency from ductile to brittle fracture with increasing the strain rate.

  9. High Temperature Oxidation and Corrosion Properties of High Entropy Superalloys

    Directory of Open Access Journals (Sweden)

    Te-Kang Tsao

    2016-02-01

    Full Text Available The present work investigates the high temperature oxidation and corrosion behaviour of high entropy superalloys (HESA. A high content of various solutes in HESA leads to formation of complex oxides, however the Cr and Al activities of HESA are sufficient to promote protective chromia or alumina formation on the surface. By comparing the oxidation and corrosion resistances of a Ni-based superalloy—CM247LC, Al2O3-forming HESA can possess comparable oxidation resistance at 1100 °C, and Cr2O3-forming HESA can exhibit superior resistance against hot corrosion at 900 °C. This work has demonstrated the potential of HESA to maintain surface stability in oxidizing and corrosive environments.

  10. Isothermal Oxidation Comparison of Three Ni-Based Superalloys

    Science.gov (United States)

    Mallikarjuna, H. T.; Richards, N. L.; Caley, W. F.

    2017-05-01

    Ni-based superalloys are used for high-temperature components of gas turbines in both industrial and aerospace applications due to their ability to maintain dimensional stability under conditions of high stress and strain. The oxidation resistance of these alloys often dictates their service lifetime. This study focuses on the isothermal oxidation behavior of three Ni-based superalloys, namely, polycrystalline cast IN738LC, single-crystal N5, and a ternary Ni-Fe-Cr (TAS) powder metallurgy alloy. The isothermal oxidation tests were conducted at 900 °C in the static air up to 1000 h, and the specific aspects studied were the oxidation behavior of these chromia-forming and alumina-forming alloys that are used extensively in industry. In particular, the behavior of oxide scale growth and subsurface changes were analyzed in detail using various techniques such as SEM, EDS, and AFM. From the isothermal oxidation kinetics, the oxidation rate constant, k p, was calculated for each alloy and found to be; k p = 2.79 × 10-6 mg2 cm-4 s-1 for IN738LC, k p = 1.42 × 10-7 mg2 cm-4 s-1 for N5 and k p = 1.62 × 10-7 mg2 cm-4 s-1 for TAS. Based on a microstructural analysis, IN738LC exhibited a continuous dense outer scale of Cr2O3 and discontinuous inner scale of Al2O3, whereas N5 and TAS showed a dense outer scale of Al2O3 alone. The results suggested that the N5 and PM-TAS alloys are more oxidation resistant than the IN738LC under these conditions.

  11. Modified Lattice Landau Gauge

    CERN Document Server

    Von Smekal, L; Sternbeck, A; Williams, A G

    2007-01-01

    We propose a modified lattice Landau gauge based on stereographically projecting the link variables on the circle S^1 -> R for compact U(1) or the 3-sphere S^3 -> R^3 for SU(2) before imposing the Landau gauge condition. This can reduce the number of Gribov copies exponentially and solves the Gribov problem in compact U(1) where it is a lattice artifact. Applied to the maximal Abelian subgroup this might be just enough to avoid the perfect cancellation amongst the Gribov copies in a lattice BRST formulation for SU(N), and thus to avoid the Neuberger 0/0 problem. The continuum limit of the Landau gauge remains unchanged.

  12. Jammed lattice sphere packings.

    Science.gov (United States)

    Kallus, Yoav; Marcotte, Étienne; Torquato, Salvatore

    2013-12-01

    We generate and study an ensemble of isostatic jammed hard-sphere lattices. These lattices are obtained by compression of a periodic system with an adaptive unit cell containing a single sphere until the point of mechanical stability. We present detailed numerical data about the densities, pair correlations, force distributions, and structure factors of such lattices. We show that this model retains many of the crucial structural features of the classical hard-sphere model and propose it as a model for the jamming and glass transitions that enables exploration of much higher dimensions than are usually accessible.

  13. Jammed lattice sphere packings

    Science.gov (United States)

    Kallus, Yoav; Marcotte, Étienne; Torquato, Salvatore

    2013-12-01

    We generate and study an ensemble of isostatic jammed hard-sphere lattices. These lattices are obtained by compression of a periodic system with an adaptive unit cell containing a single sphere until the point of mechanical stability. We present detailed numerical data about the densities, pair correlations, force distributions, and structure factors of such lattices. We show that this model retains many of the crucial structural features of the classical hard-sphere model and propose it as a model for the jamming and glass transitions that enables exploration of much higher dimensions than are usually accessible.

  14. The Improvement of Oxidation Resistance of a Re-Based Diffusion Barrier/Ni–Al Coating on the Single-Crystal Ni-Based TMS-82+ Superalloy

    NARCIS (Netherlands)

    Wu, Y.; Wang, Y.M.; Song, G.M.; Li, X.W.

    2011-01-01

    Oxidation behavior of a Re-based diffusion barrier/Ni–Al coated single-crystal (SC) Ni-based TMS-82+ superalloy was studied to compare with those of the base and Ni–Al coated superalloys under cyclic air at 1150 °C for 200 h. The base superalloy showed a negative mass gain due to extensive oxide spa

  15. High-temperature-oxidation-induced ordered structure in Inconel 939 superalloy exposed to oxy-combustion environments

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Jingxi; Wise, Adam; Nuhfer, Thomas; Holcomb, Gordon R; Jablonski, Paul D; Sridhar, Seetharaman; Laughlin, David E

    2013-04-20

    In the integrated oxy-fuel combustion and turbine power generation system, turbine alloys are exposed to high temperature and an atmosphere comprised of steam, CO2 and O2. While surface and internal oxidation of the alloy takes place, the microstructure in the subsurface region also changes due to oxidation that results in the loss of the strengthening precipitates. In an earlier study of the oxidation of Inconel 939 Ni-based superalloy exposed to oxy-fuel combustion environment for up to 1000 hours, a high-temperature-oxidation-induced phase transformation in the sub-surface region was noticed and a two-phase region formed at the expense of strengthening γ' phase. While one of the two phases was identified as the Ni-matrix (γ solid solution, face-center-cubic) phase, the other product phase remained unidentified. In this study, the crystal structure of the unknown phase and its orientation relationship with the parent Ni-matrix phase was investigated through electron diffraction and high-resolution transmission electron microscopy. It was determined that the crystal structure of the unknown phase could be modeled as a ternary derivative of the ordered η-Ni3Ti phase (D024) structure with lattice parameters of a = 0.5092 nm and c = 0.8336 nm, α = 90º, β = 90º and γ = 120º.

  16. The influence of cobalt, tantalum, and tungsten on the elevated temperature mechanical properties of single crystal nickel-base superalloys

    Science.gov (United States)

    Nathal, M. V.; Ebert, L. J.

    1985-10-01

    The influence of composition on the tensile and creep strength of [001] oriented nickel-base superalloy single crystals at temperatures near 1000 °C was investigated. Cobalt, tantalum, and tungsten concentrations were varied according to a matrix of compositions based on the single crystal version of MAR-M247.* For alloys with the baseline refractory metal level of 3 wt pct Ta and 10 wt pct W, decreases in Co level from 10 to 0 wt pct resulted in increased tensile and creep strength. Substitution of 2 wt pct W for 3 wt pct Ta resulted in decreased creep life at high stresses, but improved life at low stresses. Substitution of Ni for Ta caused large reductions in tensile strength and creep resistance, and corresponding increases in ductility. For these alloys with low Ta plus W totals, strength was independent of Co level. The effects of composition on properties were related to the microstructural features of the alloys. In general, high creep strength was associated with high levels of γ' volume fraction, γ-γ' lattice mismatch, and solid solution hardening.

  17. Truncation Effects in Monte Carlo Renormalization Group Improved Lattice Actions

    CERN Document Server

    Takaishi, T; Forcrand, Ph. de

    1998-01-01

    We study truncation effects in the SU(3) gauge actions obtained by the Monte Carlo renormalization group method. By measuring the heavy quark potential we find that the truncation effects in the actions coarsen the lattice by 40-50 % from the original blocked lattice. On the other hand, we find that rotational symmetry of the heavy quark potentials is well recovered on such coarse lattices, which may indicate that rotational symmetry breaking terms are easily cancelled out by adding a short distance operator. We also discuss the possibility of reducing truncation effects.

  18. Lattice Gerbe Theory

    CERN Document Server

    Lipstein, Arthur E

    2014-01-01

    We formulate the theory of a 2-form gauge field on a Euclidean spacetime lattice. In this approach, the fundamental degrees of freedom live on the faces of the lattice, and the action can be constructed from the sum over Wilson surfaces associated with each fundamental cube of the lattice. If we take the gauge group to be $U(1)$, the theory reduces to the well-known abelian gerbe theory in the continuum limit. We also propose a very simple and natural non-abelian generalization with gauge group $U(N) \\times U(N)$, which gives rise to $U(N)$ Yang-Mills theory upon dimensional reduction. Formulating the theory on a lattice has several other advantages. In particular, it is possible to compute many observables, such as the expectation value of Wilson surfaces, analytically at strong coupling and numerically for any value of the coupling.

  19. Root lattices and quasicrystals

    Science.gov (United States)

    Baake, M.; Joseph, D.; Kramer, P.; Schlottmann, M.

    1990-10-01

    It is shown that root lattices and their reciprocals might serve as the right pool for the construction of quasicrystalline structure models. All noncrystallographic symmetries observed so far are covered in minimal embedding with maximal symmetry.

  20. SPIN ON THE LATTICE.

    Energy Technology Data Exchange (ETDEWEB)

    ORGINOS,K.

    2003-01-07

    I review the current status of hadronic structure computations on the lattice. I describe the basic lattice techniques and difficulties and present some of the latest lattice results; in particular recent results of the RBC group using domain wall fermions are also discussed. In conclusion, lattice computations can play an important role in understanding the hadronic structure and the fundamental properties of Quantum Chromodynamics (QCD). Although some difficulties still exist, several significant steps have been made. Advances in computer technology are expected to play a significant role in pushing these computations closer to the chiral limit and in including dynamical fermions. RBC has already begun preliminary dynamical domain wall fermion computations [49] which we expect to be pushed forward with the arrival of QCD0C. In the near future, we also expect to complete the non-perturbative renormalization of the relevant derivative operators in quenched QCD.

  1. Vector Lattice Vortex Solitons

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-Dong; YE Fang-Wei; DONG Liang-Wei; LI Yong-Ping

    2005-01-01

    @@ Two-dimensional vector vortex solitons in harmonic optical lattices are investigated. The stability properties of such solitons are closely connected to the lattice depth Vo. For small Vo, vector vortex solitons with the total zero-angular momentum are more stable than those with the total nonzero-angular momentum, while for large Vo, this case is inversed. If Vo is large enough, both the types of such solitons are stable.

  2. Technicolor on the Lattice

    CERN Document Server

    Pica, C; Lucini, B; Patella, A; Rago, A

    2009-01-01

    Technicolor theories provide an elegant mechanism for dynamical electroweak symmetry breaking. We will discuss the use of lattice simulations to study the strongly-interacting dynamics of some of the candidate theories, with matter fields in representations other than the fundamental. To be viable candidates for phenomenology, such theories need to be different from a scaled-up version of QCD, which were ruled out by LEP precision measurements, and represent a challenge for modern lattice computations.

  3. Automated Lattice Perturbation Theory

    Energy Technology Data Exchange (ETDEWEB)

    Monahan, Christopher

    2014-11-01

    I review recent developments in automated lattice perturbation theory. Starting with an overview of lattice perturbation theory, I focus on the three automation packages currently "on the market": HiPPy/HPsrc, Pastor and PhySyCAl. I highlight some recent applications of these methods, particularly in B physics. In the final section I briefly discuss the related, but distinct, approach of numerical stochastic perturbation theory.

  4. Permutohedral Lattice CNNs

    OpenAIRE

    Kiefel, Martin; Jampani, Varun; Gehler, Peter V.

    2014-01-01

    This paper presents a convolutional layer that is able to process sparse input features. As an example, for image recognition problems this allows an efficient filtering of signals that do not lie on a dense grid (like pixel position), but of more general features (such as color values). The presented algorithm makes use of the permutohedral lattice data structure. The permutohedral lattice was introduced to efficiently implement a bilateral filter, a commonly used image processing operation....

  5. Solitons in spiraling Vogel lattices

    CERN Document Server

    Kartashov, Yaroslav V; Torner, Lluis

    2012-01-01

    We address light propagation in Vogel optical lattices and show that such lattices support a variety of stable soliton solutions in both self-focusing and self-defocusing media, whose propagation constants belong to domains resembling gaps in the spectrum of a truly periodic lattice. The azimuthally-rich structure of Vogel lattices allows generation of spiraling soliton motion.

  6. Influence of Short-time Oxidation on Corrosion Properties of Directionally Solidified Superalloys with Different Orientations

    Directory of Open Access Journals (Sweden)

    MA Luo-ning

    2016-07-01

    Full Text Available In order to investigate the corrosion performance on intersecting and longitudinal surfaces of unoxidized and oxidized directionally solidified superalloys, Ni-base directionally solidified superalloy DZ125 and Co-base directionally solidified superalloy DZ40M were selected. Oxidation behavior on both alloys with different orientations was investigated at 1050℃ at different times, simulating the oxidation process of vanes or blades in service; subsequent electrochemical performance in 3.5%NaCl aqueous solution was studied on two orientations of unoxidized and oxidized alloys, simulating the corrosion process of superalloy during downtime. The results show that grain boundaries and sub-boundaries of directionally solidified superalloys are susceptible to corrosion and thus longitudinal surface with lower area fraction of grain boundaries has higher corrosion resistance. Compared to intersecting surface of alloys, the structure of grain boundaries of longitudinal surface is less conducive to diffusion and thus the oxidation rate on longitudinal surface is lower. Formation of oxide layers on alloys after short-time oxidation provides protective effect and enhances the corrosion resistance.

  7. Microstructural Stability and Hot Deformation of γ- γ'- δ Ni-Base Superalloys

    Science.gov (United States)

    Detrois, Martin; Helmink, Randolph C.; Tin, Sammy

    2014-11-01

    Nickel-base superalloys exhibit excellent high-temperature mechanical and physical properties and remain the first choice for structural components in advanced gas turbine engines for the aerospace propulsion and power generation applications. In response to the increasing demand for more efficient solutions and tighter requirements linked to gas turbine technologies, the properties of nickel-base superalloys can be improved by modification of their thermo-mechanical and/or compositional attributes. Recent investigations have revealed the potential use of ternary eutectic γ- γ'- δ Ni-base superalloys in advanced gas turbines due to high temperature mechanical properties that are comparable to state-of-the-art polycrystalline Ni-base superalloys. With properties largely dependent on microstructural strengthening mechanisms, both the composition and thermo-mechanical processing parameters of this novel class of alloys need to be optimized concurrently. The hot deformation characteristics of four γ- γ'- δ Ni-base superalloys with varying levels of Nb were evaluated at temperatures and strain rates between 1353 K and 1433 K (1080 °C and 1160 °C) and 0.01 to 0.001/s, respectively. Evidence of dislocation-based plasticity was observed following deformation at low temperatures and high strain rates, while high temperatures and low strain rates promoted superplasticity in these alloys. The extent of the microstructural changes and the magnitude of the cavitation damage which occurred during deformation was found to vary as a function of the alloy composition.

  8. Study of phase transformations in CMSX-6 and CMSX-8 superalloys

    Science.gov (United States)

    Szczotok, Agnieszka; Wierzbicka-Miernik, Anna

    2014-09-01

    Nickel-based superalloys are extensively used mainly in the aircraft and aeronautic industry, particularly in the hottest parts of engines or turbo-reactors. The phase reactions occurring in these heat-resistant materials play a crucial role in many aspects of the processing and service of the highly alloyed materials. Cast Ni-based superalloys are obtained in a complex way and their structure is complicated. Differential scanning calorimetry (DSC) technique was applied for determination of temperature ranges of the phase transformations occurring in the CMSX-6 and CMSX-8 superalloys during heating/cooling processes. Thermophysical properties, including temperatures of the phase transformation, are the critical input parameters in mathematical models of solidification and casting of metallic materials. The literature data concerning phase transformations and performance of the heat treatment for CMSX-6 and CMSX-8 are incomplete and ambiguous. DSC results accompanied by scanning electron microscopy characterization of microstructure of CMSX-6 and CMSX-8 superalloy was applied. The present study will improve the understanding of the fundamental mechanisms of phase transformations of single-crystal nickel-based superalloys.

  9. Microstructural analysis of laser weld fusion zone in Haynes 282 superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Osoba, L.O. [Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg, Manitoba, R3T 5V6 (Canada); Ding, R.G. [Department of Metallurgy and Materials Engineering, University of Birmingham, Birmingham B15 2TT (United Kingdom); Ojo, O.A., E-mail: ojo@cc.umanitoba.ca [Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg, Manitoba, R3T 5V6 (Canada)

    2012-03-15

    Analytical electron microscopy and spectroscopy analyses of the fusion zone (FZ) microstructure in autogenous laser beam welded Haynes 282 (HY 282) superalloy were performed. The micro-segregation patterns observed in the FZ indicate that Co, Cr and Al exhibited a nearly uniform distribution between the dendrite core and interdendritic regions while Ti and Mo were rejected into the interdendritic liquid during the weld solidification. Transmission electron diffraction analysis and energy dispersive X-ray microanalysis revealed the second phase particles formed along the FZ interdendritic region to be Ti-Mo rich MC-type carbide particles. Weld FZ solidification cracking, which is sometimes associated with the formation of {gamma}-{gamma}' eutectic in {gamma}' precipitation strengthened nickel-base superalloys, was not observed in the HY 282 superalloy. Modified primary solidification path due to carbon addition in the newly developed superalloy is used to explain preclusion of weld FZ solidification cracking in the material. - Highlights: Black-Right-Pointing-Pointer A newly developed superalloy was welded by CO{sub 2} laser beam joining technique. Black-Right-Pointing-Pointer Electron microscopy characterization of the weld microstructure was performed. Black-Right-Pointing-Pointer Identified interdendritic microconstituents consist of MC-type carbides. Black-Right-Pointing-Pointer Modification of primary solidification path is used to explain cracking resistance.

  10. Development of a numerical procedure for mixed mode K-solutions and fatigue crack growth in FCC single crystal superalloys

    Science.gov (United States)

    Ranjan, Srikant

    2005-11-01

    Fatigue-induced failures in aircraft gas turbine and rocket engine turbopump blades and vanes are a pervasive problem. Turbine blades and vanes represent perhaps the most demanding structural applications due to the combination of high operating temperature, corrosive environment, high monotonic and cyclic stresses, long expected component lifetimes and the enormous consequence of structural failure. Single crystal nickel-base superalloy turbine blades are being utilized in rocket engine turbopumps and jet engines because of their superior creep, stress rupture, melt resistance, and thermomechanical fatigue capabilities over polycrystalline alloys. These materials have orthotropic properties making the position of the crystal lattice relative to the part geometry a significant factor in the overall analysis. Computation of stress intensity factors (SIFs) and the ability to model fatigue crack growth rate at single crystal cracks subject to mixed-mode loading conditions are important parts of developing a mechanistically based life prediction for these complex alloys. A general numerical procedure has been developed to calculate SIFs for a crack in a general anisotropic linear elastic material subject to mixed-mode loading conditions, using three-dimensional finite element analysis (FEA). The procedure does not require an a priori assumption of plane stress or plane strain conditions. The SIFs KI, KII, and KIII are shown to be a complex function of the coupled 3D crack tip displacement field. A comprehensive study of variation of SIFs as a function of crystallographic orientation, crack length, and mode-mixity ratios is presented, based on the 3D elastic orthotropic finite element modeling of tensile and Brazilian Disc (BD) specimens in specific crystal orientations. Variation of SIF through the thickness of the specimens is also analyzed. The resolved shear stress intensity coefficient or effective SIF, Krss, can be computed as a function of crack tip SIFs and the

  11. Dispersion of guided modes in two-dimensional split ring lattices

    CERN Document Server

    Lunnemann, Per

    2014-01-01

    We present a semi-analytical point-dipole method that uses Ewald lattice summation to find the dispersion relation of guided plasmonic and bianisotropic modes in metasurfaces composed of 2D periodic lattices of arbitrarily strongly scattering magneto-electric dipole scatterers. This method takes into account all retarded electrodynamic interactions as well as radiation damping selfconsistently. As illustration we analyze the dispersion of plasmon nanorod lattices, and of 2D split ring resonator lattices. Plasmon nanorod lattices support transverse and longitudinal in-plane electric modes. Scatterers that have an in-plane electric and out-of-plane magnetic polarizability, but without intrinsic magnetoelectric coupling, result in two bands that are mixtures of the bands of electric-only and magnetic-only lattices. Thereby bianisotropy through mutual coupling, in absence of building-block bianisotropy, is evident. Once strong bi-anisotropy is included in each building block, the Bloch modes become even more stro...

  12. A Bijection between Lattice-Valued Filters and Lattice-Valued Congruences in Residuated Lattices

    Directory of Open Access Journals (Sweden)

    Wei Wei

    2013-01-01

    Full Text Available The aim of this paper is to study relations between lattice-valued filters and lattice-valued congruences in residuated lattices. We introduce a new definition of congruences which just depends on the meet ∧ and the residuum →. Then it is shown that each of these congruences is automatically a universal-algebra-congruence. Also, lattice-valued filters and lattice-valued congruences are studied, and it is shown that there is a one-to-one correspondence between the set of all (lattice-valued filters and the set of all (lattice-valued congruences.

  13. Environmental effects of microstructure stability on nickel-base superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Sah, In Jin

    2011-02-15

    Next generation nuclear reactor VHTR (Very High Temperature gas-cooled Reactor) wants to achieve higher thermal efficiency and hydrogen production. IHX (Intermediate Heat eXchanger) will be exposed to the highest temperature condition among lots of structural components. Solid-solution hardening nickel-base superalloys Alloy 617 and Haynes 230 are expected to use for this applications. Studies on oxidation test and time dependent deformation at 900 .deg. C were conducted before. This study is focused on the microstructure evolution and mechanical properties at other temperature ranges. Furthermore, considering heat treatment history especially cooling rate effects on microstructure evolution, those of two superalloys are cooled down to room temperature by air and furnace. Materials behavior at intermediation temperature ranges from 600-900 .deg. C and diffusion bonding condition (1150 .deg. C) were evaluated. Vicker's hardness test and small-size tensile test were carried out for each specimen at room temperature. Hardness number and tensile strength were higher than any other temperature condition at 700 .deg. C due to gamma prime phases for Alloy 617. As the aluminum contents of Haynes 230 is far less than Alloy 617, there is no big difference for Haynes 230 at intermediate temperature ranges. The value of mechanical property of alloys at 1150 .deg. C air cooling condition was severely decreased and fully ductile fracture was detected for both alloys. On the other hand, the values showed the tendency of return to the intermediate temperature ranges when the specimen was slowly cooled down. Characteristic precipitates along the grain boundaries were detected. There was no other singularity up to 700 .deg. C for Alloy 617. However, lots of tiny M{sub 23}C{sub 6} type carbide were formed after 800 .deg. C heat treatment, and those of carbide got bigger and bigger as the heat treatment temperature increased up to 900 .deg. C. For diffusion bonding temperature

  14. Characterization of fatigue mechanisms in nickel-based superalloys

    Science.gov (United States)

    Yablinsky, Clarissa A.

    Ni-based superalloys are important for turbine engine airfoil applications. Historically, creep has been the main failure mode and thus creep mechanisms have been the subject of numerous studies. However, modern airfoil designs maintain cooler temperatures, and consequently creep is no longer the primary failure mode. Rather, in the cooled components, experience and experimental studies have shown that fatigue is the life-limiting factor. The changing cause of failure highlighted the need for a comprehensive study of fatigue deformation mechanisms. Information about crack propagation and the associated deformation mechanisms has allowed appropriate design changes based on fatigue as a life-limiting factor. The focus of the study will be on a monocrystalline Ni-based superalloy, Rene N5, which is currently used for airfoils. Compact tension specimens were tested under cyclic loading conditions to determine the influence of microstructure and material properties on crack propagation and fatigue failure. The crack growth rate as a function of temperature, environment, frequency, and crystallographic orientation was determined. High resolution scanning electron microscopy was used to examine the fracture surface on length scales from nano to macro. Deformation mechanisms in the plastic zone ahead of the crack tip and within the plastic wake of the crack were studied using TEM and FIB techniques. Environment and frequency seem to have a larger effect on fatigue crack growth rates and threshold stress intensity factor ranges, while temperature and orientation effects are present, but not as dramatic. In the normal blade orientation, (001)[100], mode I crack propagation was prevalent, with mode II crack propagation found at higher DeltaK values. Interdendritic particles appear to be slowing crack growth rates in the threshold region of specimens tested in air. Microstructural analysis showed no change in gamma' precipitate size or morphology with temperature or stress

  15. Lattice renormalization of the static quark derivative operator

    CERN Document Server

    Blossier, B; Morénas, V; Pène, O

    2006-01-01

    We give the analytical expressions and numerical values of radiative corrections to the covariant derivative operator on the static quark line, used for the lattice calculation of the Isgur-Wise form factors $\\tau_{1/2}(1)$ and $\\tau_{3/2}(1)$. Those corrections induce an enhancement of renormalized quantities if an hypercubic blocking is applied to the Wilson line, whereas there is a reduction without such a blocking.

  16. A study of microtubule dipole lattices

    Science.gov (United States)

    Nandi, Shubhendu

    Microtubules are cytoskeletal protein polymers orchestrating a host of important cellular functions including, but not limited to, cell support, cell division, cell motility and cell transport. In this thesis, we construct a toy-model of the microtubule lattice composed of vector Ising spins representing tubulin molecules, the building block of microtubules. Nearest-neighbor and next-to-nearest neighbor interactions are considered within an anisotropic dielectric medium. As a consequence of the helical topology, we observe that certain spin orientations render the lattice frustrated with nearest neighbor ferroelectric and next-to-nearest neighbor antiferroelectric bonds. Under these conditions, the lattice displays the remarkable property of stabilizing certain spin patterns that are robust to thermal fluctuations. We model this behavior in the framework of a generalized Ising model known as the J1 - J2 model and theoretically determine the set of stable patterns. Employing Monte-Carlo methods, we demonstrate the stability of such patterns in the microtubule lattice at human physiological temperatures. This suggests a novel biological mechanism for storing information in living organisms, whereby the tubulin spin (dipole moment) states become information bits and information gets stored in microtubules in a way that is robust to thermal fluctuations.

  17. Measuring on Lattices

    Science.gov (United States)

    Knuth, Kevin H.

    2009-12-01

    Previous derivations of the sum and product rules of probability theory relied on the algebraic properties of Boolean logic. Here they are derived within a more general framework based on lattice theory. The result is a new foundation of probability theory that encompasses and generalizes both the Cox and Kolmogorov formulations. In this picture probability is a bi-valuation defined on a lattice of statements that quantifies the degree to which one statement implies another. The sum rule is a constraint equation that ensures that valuations are assigned so as to not violate associativity of the lattice join and meet. The product rule is much more interesting in that there are actually two product rules: one is a constraint equation arises from associativity of the direct products of lattices, and the other a constraint equation derived from associativity of changes of context. The generality of this formalism enables one to derive the traditionally assumed condition of additivity in measure theory, as well introduce a general notion of product. To illustrate the generic utility of this novel lattice-theoretic foundation of measure, the sum and product rules are applied to number theory. Further application of these concepts to understand the foundation of quantum mechanics is described in a joint paper in this proceedings.

  18. Fermion RG blocking transformations and IR structure

    CERN Document Server

    Cheng, X

    2011-01-01

    We explore fermion RG block-spinning transformations on the lattice with the aim of studying the IR structure of gauge theories and, in particular, the existence of IR fixed points for varying fermion content. In the case of light fermions the main concern and difficulty is ensuring locality of any adopted blocking scheme. We discuss the problem of constructing a local blocked fermion action in the background of arbitrary gauge fields. We then discuss the carrying out of accompanying gauge field blocking. In the presence of the blocked fermions implementation of MCRG is not straightforward. By adopting judicious approximations we arrive at an easily implementable approximate RG recursion scheme that allows quick, inexpensive estimates of the location of conformal windows for various groups and fermion representations. We apply this scheme to locate the conformal windows in the case of SU(2) and SU(3) gauge groups. Some of the reasons for the apparent efficacy of this and similar decimation schemes are discuss...

  19. Tensile Properties and Deformation Characteristics of a Ni-Fe-Base Superalloy for Steam Boiler Applications

    Science.gov (United States)

    Zhong, Zhihong; Gu, Yuefeng; Yuan, Yong; Shi, Zhan

    2014-01-01

    Ni-Fe-base superalloys due to their good manufacturability and low cost are the proper candidates for boiler materials in advanced power plants. The major concerns with Ni-Fe-base superalloys are the insufficient mechanical properties at elevated temperatures. In this paper, tensile properties, deformation, and fracture characteristics of a Ni-Fe-base superalloy primarily strengthened by γ' precipitates have been investigated from room temperature to 1073 K (800 °C). The results showed a gradual decrease in the strength up to about 973 K (700 °C) followed by a rapid drop above this temperature and a ductility minimum at around 973 K (700 °C). The fracture surfaces were studied using scanning electron microscopy and the deformation mechanisms were determined by the observation of deformed microstructures using transmission electron microscopy. An attempt has been made to correlate the tensile properties and fracture characteristics at different temperatures with the observed deformation mechanisms.

  20. A comparative study of the corrosion resistance of incoloy MA 956 and PM 2000 superalloys

    Directory of Open Access Journals (Sweden)

    Maysa Terada

    2010-12-01

    Full Text Available Austenitic stainless steels, titanium and cobalt alloys are widely used as biomaterials. However, new medical devices require innovative materials with specific properties, depending on their application. The magnetic properties are among the properties of interest for some biomedical applications. However, due to the interaction of magnetic materials with Magnetic Resonance Image equipments they might used only as not fixed implants or for medical devices. The ferromagnetic superalloys, Incoloy MA 956 and PM 2000, produced by mechanical alloying, have similar chemical composition, high corrosion resistance and are used in high temperature applications. In this study, the corrosion resistance of these two ferritic superalloys was compared in a phosphate buffer solution. The electrochemical results showed that both superalloys are passive in this solution and the PM 2000 present a more protective passive film on it associated to higher impedances than the MA 956.

  1. Influence of Processing Parameters on Granularity Distribution of Superalloy Powders during PREP

    Institute of Scientific and Technical Information of China (English)

    Huanming CHEN; Benfu HU; Yiwen ZHANG; Huiying LI; Quanmao YU

    2003-01-01

    In order to investigate the influence of processing parameters on the granularity distribution of superalloy powders during the atomization of plasma rotating electrode processing (PREP), in this paper FGH95 superalloy powders is prepared under different processing conditions by PREP and the influence of PREP processing parameters on the granularity distribution of FGH95 superalloy powders is discussed based on fractal geometry theory. The results show that with the increase of rotating velocity of the self-consuming electrode, the fractal dimension of the granularity distribution increases linearly, which results in the increase of the proportion of smaller powders. The change of interval between plasma gun and the self-consuming electrode has a little effect on the granularity distribution, also the fractal dimension of the granularity distribution changed a little correspondingly.

  2. The Microstructure Stability of Precipitation Strengthened Medium to High Entropy Superalloys

    Science.gov (United States)

    Tsao, Te-Kang; Yeh, An-Chou; Murakami, Hideyuki

    2017-05-01

    Medium and high entropy superalloys based on the Ni-Co-Fe system with strengthening L12 γ' precipitates have been developed. The present study has shown that by controlling the elemental partitioning between γ/γ', thermal stability of γ' can be enhanced in the high entropy γ matrix. Most importantly, high entropy superalloys exhibit stable γ-γ' microstructures with no TCP phases after long-term exposure at elevated temperatures. Therefore, a new alloy design space for stable γ-γ' microstructure has been presented. Furthermore, due to relatively high content of Fe and Ti, their raw materials cost and alloy density can potentially be lower than those of conventional superalloys.

  3. Alloying effects of refractory elements in the dislocation of Ni-based single crystal superalloys

    Directory of Open Access Journals (Sweden)

    Shiyu Ma

    2016-12-01

    Full Text Available The alloying effects of W, Cr and Re in the [100] (010 edge dislocation cores (EDC of Ni-based single crystal superalloys are investigated using first-principles based on the density functional theory (DFT. The binding energy, Mulliken orbital population, density of states, charge density and radial distribution functions are discussed, respectively. It is clearly demonstrated that the addition of refractory elements improves the stability of the EDC systems. In addition, they can form tougher bonds with their nearest neighbour (NN Ni atoms, which enhance the mechanical properties of the Ni-based single crystal superalloys. Through comparative analysis, Cr-doped system has lower binding energy, and Cr atom has evident effect to improve the systemic stability. However, Re atom has the stronger alloying effect in Ni-based single crystal superalloys, much more effectively hindering dislocation motion than W and Cr atoms.

  4. New approach for assessing the weldability of precipitation-strengthened nickel-base superalloys

    Institute of Scientific and Technical Information of China (English)

    Homam Naff akh Moosavy; Mohammad-Reza Aboutalebi; Seyed Hossein Seyedein; Meisam Khodabakhshi; Carlo Mapelli

    2013-01-01

    A new procedure was proposed for evaluating the weldability of nickel-base superalloys. The theory is on the basis of two microstructural patterns. In pattern I, the weld microstructure exhibits severe alloying segregation, many low-melting eutectic structures, and low weldability. The weld requires a weaker etchant and a shorter time for etching. In pattern II, the weld microstructure displays less alloying segregation, low quantity of eutectic structures, and high weldability. The weld needs a stronger etchant and a longer time for etching. Five superalloys containing diff erent amounts of Nb and Ti were designed to verify the patterns. After welding operations, the welds were etched by four etchants with diff erent corrosivities. The weldability was determined by TG-DSC measurements. The metallography and weldability results confirmed the theoretic patterns. Finally, the etchant corrosivity and etching time were proposed as new criteria to evaluate the weldability of nickel-base superalloys.

  5. New approach for assessing the weldability of precipitation-strengthened nickel-base superalloys

    Science.gov (United States)

    Moosavy, Homam Naffakh; Aboutalebi, Mohammad-Reza; Seyedein, Seyed Hossein; Khodabakhshi, Meisam; Mapelli, Carlo

    2013-12-01

    A new procedure was proposed for evaluating the weldability of nickel-base superalloys. The theory is on the basis of two microstructural patterns. In pattern I, the weld microstructure exhibits severe alloying segregation, many low-melting eutectic structures, and low weldability. The weld requires a weaker etchant and a shorter time for etching. In pattern II, the weld microstructure displays less alloying segregation, low quantity of eutectic structures, and high weldability. The weld needs a stronger etchant and a longer time for etching. Five superalloys containing different amounts of Nb and Ti were designed to verify the patterns. After welding operations, the welds were etched by four etchants with different corrosivities. The weldability was determined by TG-DSC measurements. The metallography and weldability results confirmed the theoretic patterns. Finally, the etchant corrosivity and etching time were proposed as new criteria to evaluate the weldability of nickel-base superalloys.

  6. Quantitative evaluation of carbides in nickel-base superalloy MAR-M247

    Science.gov (United States)

    Szczotok, A.

    2011-05-01

    It has been established that carbides in superalloys serve three functions. Fine carbides precipitated in the matrix give strengthening results. Carbides also can tie up certain elements that would otherwise promote phase instability during service. Grain boundary carbides prevent or retard grain-boundary sliding and strengthen the grain boundary, which depends significantly on carbide shape, size and distribution. Various types of carbides are possible, depending on superalloy composition and processing. In the paper optical and scanning electron microscopy investigations of carbides occurring in specimens of the polycrystalline nickel-base superalloy MAR-M247 were carried out. Conditions of carbides revealing and microstructure images acquisition have been described. Taking into consideration distribution and morphology of the carbides in matrix a method of quantitative description of Chinese script-like and blocky primary carbides on the basis of image analysis was proposed.

  7. Lattice Boltzmann Stokesian dynamics.

    Science.gov (United States)

    Ding, E J

    2015-11-01

    Lattice Boltzmann Stokesian dynamics (LBSD) is presented for simulation of particle suspension in Stokes flows. This method is developed from Stokesian dynamics (SD) with resistance and mobility matrices calculated using the time-independent lattice Boltzmann algorithm (TILBA). TILBA is distinguished from the traditional lattice Boltzmann method (LBM) in that a background matrix is generated prior to the calculation. The background matrix, once generated, can be reused for calculations for different scenarios, thus the computational cost for each such subsequent calculation is significantly reduced. The LBSD inherits the merits of the SD where both near- and far-field interactions are considered. It also inherits the merits of the LBM that the computational cost is almost independent of the particle shape.

  8. Lattice gauge theories

    Science.gov (United States)

    Weisz, Peter; Majumdar, Pushan

    2012-03-01

    Lattice gauge theory is a formulation of quantum field theory with gauge symmetries on a space-time lattice. This formulation is particularly suitable for describing hadronic phenomena. In this article we review the present status of lattice QCD. We outline some of the computational methods, discuss some phenomenological applications and a variety of non-perturbative topics. The list of references is severely incomplete, the ones we have included are text books or reviews and a few subjectively selected papers. Kronfeld and Quigg (2010) supply a reasonably comprehensive set of QCD references. We apologize for the fact that have not covered many important topics such as QCD at finite density and heavy quark effective theory adequately, and mention some of them only in the last section "In Brief". These topics should be considered in further Scholarpedia articles.

  9. Improved Lattice Radial Quantization

    CERN Document Server

    Brower, Richard C; Fleming, George T

    2014-01-01

    Lattice radial quantization was proposed in a recent paper by Brower, Fleming and Neuberger[1] as a nonperturbative method especially suited to numerically solve Euclidean conformal field theories. The lessons learned from the lattice radial quantization of the 3D Ising model on a longitudinal cylinder with 2D Icosahedral cross-section suggested the need for an improved discretization. We consider here the use of the Finite Element Methods(FEM) to descretize the universally-equivalent $\\phi^4$ Lagrangian on $\\mathbb R \\times \\mathbb S^2$. It is argued that this lattice regularization will approach the exact conformal theory at the Wilson-Fisher fixed point in the continuum. Numerical tests are underway to support this conjecture.

  10. Graphene antidot lattice waveguides

    DEFF Research Database (Denmark)

    Pedersen, Jesper Goor; Gunst, Tue; Markussen, Troels

    2012-01-01

    We introduce graphene antidot lattice waveguides: nanostructured graphene where a region of pristine graphene is sandwiched between regions of graphene antidot lattices. The band gaps in the surrounding antidot lattices enable localized states to emerge in the central waveguide region. We model...... the waveguides via a position-dependent mass term in the Dirac approximation of graphene and arrive at analytical results for the dispersion relation and spinor eigenstates of the localized waveguide modes. To include atomistic details we also use a tight-binding model, which is in excellent agreement...... with the analytical results. The waveguides resemble graphene nanoribbons, but without the particular properties of ribbons that emerge due to the details of the edge. We show that electrons can be guided through kinks without additional resistance and that transport through the waveguides is robust against...

  11. Digital lattice gauge theories

    CERN Document Server

    Zohar, Erez; Reznik, Benni; Cirac, J Ignacio

    2016-01-01

    We propose a general scheme for a digital construction of lattice gauge theories with dynamical fermions. In this method, the four-body interactions arising in models with $2+1$ dimensions and higher, are obtained stroboscopically, through a sequence of two-body interactions with ancillary degrees of freedom. This yields stronger interactions than the ones obtained through pertubative methods, as typically done in previous proposals, and removes an important bottleneck in the road towards experimental realizations. The scheme applies to generic gauge theories with Lie or finite symmetry groups, both Abelian and non-Abelian. As a concrete example, we present the construction of a digital quantum simulator for a $\\mathbb{Z}_{3}$ lattice gauge theory with dynamical fermionic matter in $2+1$ dimensions, using ultracold atoms in optical lattices, involving three atomic species, representing the matter, gauge and auxiliary degrees of freedom, that are separated in three different layers. By moving the ancilla atoms...

  12. Mechanical properties and development of supersolvus heat treated new nickel base superalloy AD730TM

    Directory of Open Access Journals (Sweden)

    Devaux A.

    2014-01-01

    Full Text Available The enhancement of efficiency in power generation gas turbine requires the development of new superalloys capable of withstanding higher temperatures. The development of AD730TM superalloy was achieved to provide to this new cast & wrought (C&W superalloy a higher combination between mechanical properties, microstructural stability and cost than that of other C&W superalloys with a temperature capability up to 750 ∘C. Supersolvus heat-treatment of AD730TM was studied to improve the creep properties of fine grain AD730TM superalloy which were not high enough to reach the foreseen conditions of future power generation gas turbine disks. Firstly, the grain growth was studied to select the supersolvus temperature 1120 ∘C and to obtain a homogeneous coarse grain microstructure. Then, various supersolvus heat-treatments with different cycles were tested and applied on a forged pancake with a section representative of power generation gas turbine disk. The average grain size was evaluated to be close to 200 μm for all heat-treatments. Tensile, creep, fatigue and fatigue crack growth tests were performed to compare the various heat-treatments. FEG-SEM examinations were also realized to discuss the relationships between heat-treatment, intragranular gamma prime precipitation and mechanical properties. Finally, a comparison made with other supersolvus heat treated C&W superalloys shows that AD730TM properties obtained with coarse grain microstructure are at the expected level and enable applications for power generation gas turbine discs.

  13. A Review on Inertia and Linear Friction Welding of Ni-Based Superalloys

    Science.gov (United States)

    Chamanfar, Ahmad; Jahazi, Mohammad; Cormier, Jonathan

    2015-04-01

    Inertia and linear friction welding are being increasingly used for near-net-shape manufacturing of high-value materials in aerospace and power generation gas turbines because of providing a better quality joint and offering many advantages over conventional fusion welding and mechanical joining techniques. In this paper, the published works up-to-date on inertia and linear friction welding of Ni-based superalloys are reviewed with the objective to make clarifications on discrepancies and uncertainties reported in literature regarding issues related to these two friction welding processes as well as microstructure, texture, and mechanical properties of the Ni-based superalloy weldments. Initially, the chemical composition and microstructure of Ni-based superalloys that contribute to the quality of the joint are reviewed briefly. Then, problems related to fusion welding of these alloys are addressed with due consideration of inertia and linear friction welding as alternative techniques. The fundamentals of inertia and linear friction welding processes are analyzed next with emphasis on the bonding mechanisms and evolution of temperature and strain rate across the weld interface. Microstructural features, texture development, residual stresses, and mechanical properties of similar and dissimilar polycrystalline and single crystal Ni-based superalloy weldments are discussed next. Then, application of inertia and linear friction welding for joining Ni-based superalloys and related advantages over fusion welding, mechanical joining, and machining are explained briefly. Finally, present scientific and technological challenges facing inertia and linear friction welding of Ni-based superalloys including those related to modeling of these processes are addressed.

  14. The contrasting roles of creep and stress relaxation in the time-dependent deformation during in-situ cooling of a nickel-base single crystal superalloy.

    Science.gov (United States)

    Panwisawas, Chinnapat; D'Souza, Neil; Collins, David M; Bhowmik, Ayan

    2017-09-11

    Time dependent plastic deformation in a single crystal nickel-base superalloy during cooling from casting relevant temperatures has been studied using a combination of in-situ neutron diffraction, transmission electron microscopy and modelling. Visco-plastic deformation during cooling was found to be dependent on the stress and constraints imposed to component contraction during cooling, which mechanistically comprises creep and stress relaxation. Creep results in progressive work hardening with dislocations shearing the γ' precipitates, a high dislocation density in the γ channels and near the γ/γ' interface and precipitate shearing. When macroscopic contraction is restricted, relaxation dominates. This leads to work softening from a decreased dislocation density and the presence of long segment stacking faults in γ phase. Changes in lattice strains occur to a similar magnitude in both the γ and γ' phases during stress relaxation, while in creep there is no clear monotonic trend in lattice strain in the γ phase, but only a marginal increase in the γ' precipitates. Using a visco-plastic law derived from in-situ experiments, the experimentally measured and calculated stresses during cooling show a good agreement when creep predominates. However, when stress relaxation dominates accounting for the decrease in dislocation density during cooling is essential.

  15. Optical Lattice Clocks

    Science.gov (United States)

    Oates, Chris

    2012-06-01

    Since they were first proposed in 2003 [1], optical lattice clocks have become one of the leading technologies for the next generation of atomic clocks, which will be used for advanced timing applications and in tests of fundamental physics [2]. These clocks are based on stabilized lasers whose frequency is ultimately referenced to an ultra-narrow neutral atom transition (natural linewidths magic'' value so as to yield a vanishing net AC Stark shift for the clock transition. As a result lattice clocks have demonstrated the capability of generating high stability clock signals with small absolute uncertainties (˜ 1 part in 10^16). In this presentation I will first give an overview of the field, which now includes three different atomic species. I will then use experiments with Yb performed in our laboratory to illustrate the key features of a lattice clock. Our research has included the development of state-of-the-art optical cavities enabling ultra-high-resolution optical spectroscopy (1 Hz linewidth). Together with the large atom number in the optical lattice, we are able to achieve very low clock instability (< 0.3 Hz in 1 s) [3]. Furthermore, I will show results from some of our recent investigations of key shifts for the Yb lattice clock, including high precision measurements of ultracold atom-atom interactions in the lattice and the dc Stark effect for the Yb clock transition (necessary for the evaluation of blackbody radiation shifts). [4pt] [1] H. Katori, M. Takamoto, V. G. Pal'chikov, and V. D. Ovsiannikov, Phys. Rev. Lett. 91, 173005 (2003). [0pt] [2] Andrei Derevianko and Hidetoshi Katori, Rev. Mod. Phys. 83, 331 (2011). [0pt] [3] Y. Y. Jiang, A. D. Ludlow, N. D. Lemke, R. W. Fox, J. A. Sherman, L.-S. Ma, and C. W. Oates, Nature Photonics 5, 158 (2011).

  16. Exact Lattice Supersymmetry

    Energy Technology Data Exchange (ETDEWEB)

    Catterall, Simon; Kaplan, David B.; Unsal, Mithat

    2009-03-31

    We provide an introduction to recent lattice formulations of supersymmetric theories which are invariant under one or more real supersymmetries at nonzero lattice spacing. These include the especially interesting case of N = 4 SYM in four dimensions. We discuss approaches based both on twisted supersymmetry and orbifold-deconstruction techniques and show their equivalence in the case of gauge theories. The presence of an exact supersymmetry reduces and in some cases eliminates the need for fine tuning to achieve a continuum limit invariant under the full supersymmetry of the target theory. We discuss open problems.

  17. Belief functions on lattices

    CERN Document Server

    Grabisch, Michel

    2008-01-01

    We extend the notion of belief function to the case where the underlying structure is no more the Boolean lattice of subsets of some universal set, but any lattice, which we will endow with a minimal set of properties according to our needs. We show that all classical constructions and definitions (e.g., mass allocation, commonality function, plausibility functions, necessity measures with nested focal elements, possibility distributions, Dempster rule of combination, decomposition w.r.t. simple support functions, etc.) remain valid in this general setting. Moreover, our proof of decomposition of belief functions into simple support functions is much simpler and general than the original one by Shafer.

  18. What is the role of rhenium in single crystal superalloys?

    Directory of Open Access Journals (Sweden)

    Mottura Alessandro

    2014-01-01

    Full Text Available Rhenium plays a critical role in single-crystal superalloys –its addition to first generation alloys improves creep life by a factor of at least two, with further benefits for fatigue performance. Its use in alloys such as PWA1484, CMSX-4 and Rene N5 is now widespread, and many in this community regard Re as the “magic dust”. In this paper, the latest thinking concerning the origins of the “rhenium-effect” is presented. We start by reviewing the hypothesis that rhenium clusters represent barriers to dislocation motion. Recent atom probe tomography experiments have shown that Re may instead form a solid solution with Ni at low concentrations (< 7 at.%. Density functional theory calculations indicate that, in the solid solution, short range ordering of Re may be expected. Finally, Re has been shown to diffuse slowly in the γ-Ni phase. Calculations using a semi-analytical dislocation climb/glide model based upon the work of McLean and Dyson have been used to rationalise the composition-dependence of creep deformation in these materials. All evidence points to two important factors: (i the preferred partitioning of Re to the γ phase, where dislocation activity preferentially occurs during the tertiary creep regime and (ii a retardation effect on dislocation segments at γ/γ′ interfaces, which require non-conservative climb and thus an associated vacancy flux.

  19. High Temperature Deformation Mechanisms in a DLD Nickel Superalloy

    Directory of Open Access Journals (Sweden)

    Sean Davies

    2017-04-01

    Full Text Available The realisation of employing Additive Layer Manufacturing (ALM technologies to produce components in the aerospace industry is significantly increasing. This can be attributed to their ability to offer the near-net shape fabrication of fully dense components with a high potential for geometrical optimisation, all of which contribute to subsequent reductions in material wastage and component weight. However, the influence of this manufacturing route on the properties of aerospace alloys must first be fully understood before being actively applied in-service. Specimens from the nickel superalloy C263 have been manufactured using Powder Bed Direct Laser Deposition (PB-DLD, each with unique post-processing conditions. These variables include two build orientations, vertical and horizontal, and two different heat treatments. The effects of build orientation and post-process heat treatments on the materials’ mechanical properties have been assessed with the Small Punch Tensile (SPT test technique, a practical test method given the limited availability of PB-DLD consolidated material. SPT testing was also conducted on a cast C263 variant to compare with PB-DLD derivatives. At both room and elevated temperature conditions, differences in mechanical performances arose between each material variant. This was found to be instigated by microstructural variations exposed through microscopic and Energy Dispersive X-ray Spectroscopy (EDS analysis. SPT results were also compared with available uniaxial tensile data in terms of SPT peak and yield load against uniaxial ultimate tensile and yield strength.

  20. Structural Performance of Inconel 625 Superalloy Brazed Joints

    Science.gov (United States)

    Chen, Jianqiang; Demers, Vincent; Cadotte, Eve-Line; Turner, Daniel; Bocher, Philippe

    2016-12-01

    The purpose of this work was to investigate tensile and fatigue behaviors of Inconel 625 superalloy brazed joints after transient liquid-phase bonding process. Brazing was performed in a vacuum furnace using a nickel-based filler metal in a form of paste to join wrought Inconel 625 plates. Mechanical tests were carried out on single-lap joints under various lap distance-to-thickness ratios. The fatigue crack initiation and crack growth modes were examined via metallographic analysis, and the effect of local stress on fatigue life was assessed by finite element simulations. The fatigue results show that fatigue strength and endurance limit increase with overlap distance, leading to a relatively large scatter of results. Fatigue cracks nucleated in the high-stressed region of the weld fillets from brittle eutectic phases or from internal brazing cavities. The present work proposes to rationalize the results by using the local stress at the brazing fillet. When using this local stress, all fatigue-obtained results find themselves on a single S-N curve, providing a design curve for any joint configuration in fatigue solicitation.

  1. Laser repairing surface crack of Ni-based superalloy components

    Institute of Scientific and Technical Information of China (English)

    王忠柯; 叶和清; 许德胜; 黄索逸

    2001-01-01

    Surface crack of components of the cast nickel-base superalloy was repaired with twin laser beams under proper technological conditions. One laser beam was used to melt the substrate material of crack, and the other to fill in powder material to the crack region. The experimental results show that the surface crack with the width of 0.1~0.3mm could be repaired under the laser power of 3kW and the scanning speed of 6~8mm/s. The repaired deepness of crack region is below 6.5mm. The microstructure of repaired region is the cellular crystal, columnar crystal dendrite crystal from the transition region to the top filled layer. The phases in repaired region mainly consisted of supersaturated α-Co with plenty of Ni, some Cr and Al, Cr23C6, Co2B, Co-Ni-Mo, Ni4B3, TiSi and VSi. The hardness of filled layer in repaired region ranged from HV0.2450 to HV0.2500, and the hardness decreases gradually from the filled layer to joined zone.

  2. Characterization of a Rapidly Solidified Iron-Based Superalloy

    Science.gov (United States)

    Smugeresky, J. E.

    1982-09-01

    Rapidly-solidified powders of an iron-based superalloy were characterized before and after consolidation by hot isostatic pressing. Powders made by inert gas atomization were compared to powders made by centrifugal atomization. Although many of the powder characteristics were similar, the microstructures were not. The inert gas atomized powder structure is cellular while the centrifugally atomized powder structure is dendritic. In general the finer powder particles have the finer micro-structure with the effect more noticeable in centrifugally atomized powders. After consolidation, the differences in microstructure are more dependent on the consolidation temperature and post-consolidation heat treatment than in the powder type or size. Higher consolidation temperatures and/or post-consolidation heat treatment will result in transformation of the as-solidified microstructures. The transformed microstructure and the mechanical properties can in some cases be related to the as-solidified structure. Heat treatment is needed to obtain mechanical properties equivalent to those of ingot metallurgy processed material.

  3. Friction Freeform Fabrication of Superalloy Inconel 718: Prospects and Problems

    Science.gov (United States)

    Dilip, J. J. S.; Janaki Ram, G. D.

    2013-12-01

    Friction Freeform Fabrication is a new solid-state additive manufacturing process. The present investigation reports a detailed study on the prospects of this process for additive part fabrication in superalloy Inconel 718. Using a rotary friction welding machine and employing alloy 718 consumable rods in solution treated condition, cylindrical-shaped multi-layer friction deposits (10 mm diameter) were successfully produced. In the as-deposited condition, the deposits showed very fine grain size with no grain boundary δ phase. The deposits responded well to direct aging and showed satisfactory room-temperature tensile properties. However, their stress rupture performance was unsatisfactory because of their layered microstructure with very fine grain size and no grain boundary δ phase. The problem was overcome by heat treating the deposits first at 1353 K (1080 °C) (for increasing the grain size) and then at 1223 K (950 °C) (for precipitating the δ phase). Overall, the current study shows that Friction Freeform Fabrication is a very useful process for additive part fabrication in alloy 718.

  4. Properties of GH4169 Superalloy Characterized by Nonlinear Ultrasonic Waves

    Directory of Open Access Journals (Sweden)

    Hongjuan Yan

    2015-01-01

    Full Text Available The nonlinear wave motion equation is solved by the perturbation method. The nonlinear ultrasonic coefficients β and δ are related to the fundamental and harmonic amplitudes. The nonlinear ultrasonic testing system is used to detect received signals during tensile testing and bending fatigue testing of GH4169 superalloy. The results show that the curves of nonlinear ultrasonic parameters as a function of tensile stress or fatigue life are approximately saddle. There are two stages in relationship curves of relative nonlinear coefficients β′ and δ′ versus stress and fatigue life. The relative nonlinear coefficients β′ and δ′ increase with tensile stress when tensile stress is lower than 65.8% of the yield strength, and they decrease with tensile stress when tensile stress is higher than 65.8% of the yield strength. The nonlinear coefficients have the extreme values at 53.3% of fatigue life. For the second order relative nonlinear coefficient β′, there is good agreement between the experimental data and the comprehensive model. For the third order relative nonlinear coefficient δ′, however, the experiment data does not accord with the theoretical model.

  5. ISOTHERMAL AND THERMOMECHANICAL FATIGUE OF A NICKEL-BASE SUPERALLOY

    Directory of Open Access Journals (Sweden)

    Carlos Carvalho Engler-Pinto Júnior

    2014-06-01

    Full Text Available Thermal gradients arising during transient regimes of start-up and shutdown operations produce a complex thermal and mechanical fatigue loading which limits the life of turbine blades and other engine components operating at high temperatures. More accurate and reliable assessment under non-isothermal fatigue becomes therefore mandatory. This paper investigates the nickel base superalloy CM 247LC-DS under isothermal low cycle fatigue (LCF and thermomechanical fatigue (TMF. Test temperatures range from 600°C to 1,000°C. The behavior of the alloy is strongly affected by the temperature variation, especially in the 800°C-1,000°C range. The Ramberg-Osgood equation fits very well the observed isothermal behavior for the whole temperature range. The simplified non-isothermal stress-strain model based on linear plasticity proposed to represent the thermo-mechanical fatigue behavior was able to reproduce the observed behavior for both in-phase and out-of-phase TMF cycling.

  6. Temperature Dependent Cyclic Deformation Mechanisms in Haynes 188 Superalloy

    Science.gov (United States)

    Rao, K. Bhanu Sankara; Castelli, Michael G.; Allen, Gorden P.; Ellis, John R.

    1995-01-01

    The cyclic deformation behavior of a wrought cobalt-base superalloy, Haynes 188, has been investigated over a range of temperatures between 25 and 1000 C under isothermal and in-phase thermomechanical fatigue (TMF) conditions. Constant mechanical strain rates (epsilon-dot) of 10(exp -3)/s and 10(exp -4)/s were examined with a fully reversed strain range of 0.8%. Particular attention was given to the effects of dynamic strain aging (DSA) on the stress-strain response and low cycle fatigue life. A correlation between cyclic deformation behavior and microstructural substructure was made through detailed transmission electron microscopy. Although DSA was found to occur over a wide temperature range between approximately 300 and 750 C the microstructural characteristics and the deformation mechanisms responsible for DSA varied considerably and were dependent upon temperature. In general, the operation of DSA processes led to a maximum of the cyclic stress amplitude at 650 C and was accompanied by pronounced planar slip, relatively high dislocation density, and the generation of stacking faults. DSA was evidenced through a combination of phenomena, including serrated yielding, an inverse dependence of the maximum cyclic hardening with epsilon-dot, and an instantaneous inverse epsilon-dot sensitivity verified by specialized epsilon-dot -change tests. The TMF cyclic hardening behavior of the alloy appeared to be dictated by the substructural changes occuring at the maximum temperature in the TMF cycle.

  7. Microstructure stability: Optimisation of 263 Ni-based superalloy

    Directory of Open Access Journals (Sweden)

    Crozet Coraline

    2014-01-01

    Full Text Available To reduce CO2 emissions on coal-fired power plant, A-ultra supercritical (A-USC power plant whose steam conditions exceed 700 °C are being developed. At these elevated temperatures, the use of Ni-base superalloys becomes necessary. In this context and within the European project NextGenPower, focus is made on commercial Nimonic C-263 as a candidate material for turbine rotors. Nimonic C-263 is known to have low sensitivity to segregation, high workability and high weldability which are major properties for the manufacture of large shafts. Long-term creep strength is also required for this application and unfortunately Nimonic C-263 shows η-phase precipitation after long-time exposure between 700 °C–900 °C which is detrimental for long-term creep properties. The composition of Nimonic C-263 was thus optimised to overcome the formation of η-phase. Trial tests were made in order to study the effect of hardening contribution elements on microstructural and mechanical properties. Then, a 500 mm diameter forged rotor was made from optimised 263 alloy and shows promising properties.

  8. Kinetics of Grain Growth in 718 Ni-Base Superalloy

    Directory of Open Access Journals (Sweden)

    Huda Z.

    2014-10-01

    Full Text Available The Haynes® 718 Ni-base superalloy has been investigated by use of modern material characterization, metallographic and heat treatment equipment. Grain growth annealing experiments at temperatures in the range of 1050 – 1200 oC (1323–1473K for time durations in the range of 20 min-22h have been conducted. The kinetic equations and an Arrhenius-type equation have been applied to compute the grain-growth exponent n and the activation energy for grain growth, Qg, for the investigated alloy. The grain growth exponent, n, was computed to be in the range of 0.066-0.206; and the n values have been critically discussed in relation to the literature. The activation energy for grain growth, Qg, for the investigated alloy has been computed to be around 440 kJ/mol; and the Qg data for the investigated alloy has been compared with other metals and alloys and ceramics; and critically analyzed in relation to our results.

  9. FATIGUE CRACK PROPAGATION OF Ni-BASE SUPERALLOYS

    Institute of Scientific and Technical Information of China (English)

    X.B.Liu; L.Z.Ma; K.M.Chang; E.Barbero

    2005-01-01

    Time-dependent Fatigue Crack Propagation (FCP) behaviors of five Ni-base superalloys were investigated at various temperatures under fatigue with various holding times and sustained loading conditions.The new concept of damage zone is defined and employed to evaluate the alloys' resistance to hold-time FCP.A special testing procedure is designed to get the maximum damage zone of the alloys.Udimet 720 and Waspaloy show shorter damage zones than alloys 706 and 718.The fractographical analyses show that the fracture surfaces of the specimens under hold-time fatigue conditions are mixtures with intergranular and transgranular modes.As the extension of holding time per cycle, the portion of intergranular fracture increases.The effects of loading stress intensity, temperature, holding time, alloy chemistry, and alloy microstructure on damage zone and the crack growth behaviors are studied.Hold-time usually increases the alloy's FCP rate, but there are few exemptions.For instance, the steady state hold-time FCP rate of Waspaloy at 760℃ is lower than that without hold-time.The beneficial effect of hold-time was attributed to the creep caused stress relaxation during the hold-time.

  10. Anisotropy of nickel-base superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.; Maier, R. D.; Dreshfield, R. L.

    1980-01-01

    The effects of crystal orientation on the mechanical properties of single crystals of the nickel-based superalloy Mar-M247 are investigated. Tensile tests at temperatures from 23 to 1093 C and stress rupture tests at temperatures from 760 to 1038 C were performed for 52 single crystals at various orientations. During tensile testing between 23 and 760 C, single crystals with high Schmid factors were found to be favorably oriented for slip and to exhibit lower strength and higher ductility than those with low Schmid factors. Crystals which required large rotations to become oriented for cross slip were observed to have the shortest stress rupture lives at 760 C, while those which required little or no rotation had the longest lives. In addition, stereographic triangles obtained for Mar-M247 and Mar-M200 single crystals reveal that crystals with orientations near the -111 had the highest lives, those near the 001 had high lives, and those near the 011 had low lives.

  11. Microstructural and Chemical Rejuvenation of a Ni-Based Superalloy

    Science.gov (United States)

    Yao, Zhiqi; Degnan, Craig C.; Jepson, Mark A. E.; Thomson, Rachel C.

    2016-10-01

    The microstructural evolution of the Ni-based superalloy CMSX-4 including the change in gamma prime morphology, size, and distribution after high-temperature degradation and subsequent rejuvenation heat treatments has been examined using field emission gun scanning electron microscopy and transmission electron microscopy. In this paper, it is shown that there are significant differences in the size of the `channels' between gamma prime particles, the degree of rafting, and the size of tertiary gamma prime particles in each of the different microstructural conditions studied. Chemical analysis has been carried out to compare rejuvenated and pre-service samples after the same subsequent degradation procedure. The results indicate that although the microstructures of pre-service and rejuvenated samples are similar, chemical differences are more pronounced in the rejuvenated samples, suggesting that chemical segregation from partitioning of the elements was not completely eliminated through the applied rejuvenation heat treatment. A number of modified rejuvenation heat treatment trials were carried out to reduce the chemical segregation prior to creep testing. The creep test results suggest that chemical segregation has an immeasurable influence on the short-term mechanical properties under the test conditions used here, indicating that further work is required to fully understand the suitability of specific rejuvenation heat treatments and their role in the extension of component life in power plant applications.

  12. Fatigue crack propagation in turbine disks of EI698 superalloy

    Directory of Open Access Journals (Sweden)

    A.A. Shanyavskiy

    2013-04-01

    Full Text Available In-service fatigue cracking of turbine disks of EI698 superalloy is discussed based on crack growth analyses. In the bolt joint for disks to shaft connecting there is high level of stress-state, which directed to earlier in-disks fatigue crack origination in low-cycle-fatigue regime. Fracture surface pattern such as fatigue striations were used for their spacing measurement and crack growth duration estimating. Developed disk tests on a special bench by the equivalent program to in-service cyclic loads have allowed discovering one-to-one correlation between fatigue striation spacing and crack increment in one flight. Number of fatigue striations and beach-marks calculations permitted to estimate crack growth period for the different stages of in-service disks cracking. Equivalent stress level for in-service cracked disks was calculated and compared with stress-level in-tested disks under stress equivalent program to in-service operated cyclic loads. Based on this result non-destructive inspection intervals were discussed and recommended for in-service disks in dependence on number of their flights at the moment of developed inspection to exclude in-flight disks fast fracture.

  13. Anisotropy of nickel-base superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.; Maier, R. D.; Dreshfield, R. L.

    1980-01-01

    The effects of crystal orientation on the mechanical properties of single crystals of the nickel-based superalloy Mar-M247 are investigated. Tensile tests at temperatures from 23 to 1093 C and stress rupture tests at temperatures from 760 to 1038 C were performed for 52 single crystals at various orientations. During tensile testing between 23 and 760 C, single crystals with high Schmid factors were found to be favorably oriented for slip and to exhibit lower strength and higher ductility than those with low Schmid factors. Crystals which required large rotations to become oriented for cross slip were observed to have the shortest stress rupture lives at 760 C, while those which required little or no rotation had the longest lives. In addition, stereographic triangles obtained for Mar-M247 and Mar-M200 single crystals reveal that crystals with orientations near the -111 had the highest lives, those near the 001 had high lives, and those near the 011 had low lives.

  14. Microstructural and Chemical Rejuvenation of a Ni-Based Superalloy

    Science.gov (United States)

    Yao, Zhiqi; Degnan, Craig C.; Jepson, Mark A. E.; Thomson, Rachel C.

    2016-12-01

    The microstructural evolution of the Ni-based superalloy CMSX-4 including the change in gamma prime morphology, size, and distribution after high-temperature degradation and subsequent rejuvenation heat treatments has been examined using field emission gun scanning electron microscopy and transmission electron microscopy. In this paper, it is shown that there are significant differences in the size of the `channels' between gamma prime particles, the degree of rafting, and the size of tertiary gamma prime particles in each of the different microstructural conditions studied. Chemical analysis has been carried out to compare rejuvenated and pre-service samples after the same subsequent degradation procedure. The results indicate that although the microstructures of pre-service and rejuvenated samples are similar, chemical differences are more pronounced in the rejuvenated samples, suggesting that chemical segregation from partitioning of the elements was not completely eliminated through the applied rejuvenation heat treatment. A number of modified rejuvenation heat treatment trials were carried out to reduce the chemical segregation prior to creep testing. The creep test results suggest that chemical segregation has an immeasurable influence on the short-term mechanical properties under the test conditions used here, indicating that further work is required to fully understand the suitability of specific rejuvenation heat treatments and their role in the extension of component life in power plant applications.

  15. Notch Fatigue Strength of a PM Disk Superalloy

    Science.gov (United States)

    Gayda, John; Gabb, Timothy P.; Telesman, Jack

    2007-01-01

    New powder metallurgy (PM) disk superalloys, such as ME3, LSHR, and Alloy 10, have been developed in recent years which enable rim temperatures in turbine disk applications to approach 1300 F. Before these alloys can be utilized at 1300 F their long term durability must be ensured. One of the key requirements for disk rims is notch fatigue strength. This issue is extremely important and is a direct result of the blade attachment geometry employed at the disk rim. Further, the imposition of a dwell at maximum load, associated with take off and landing, can also affect notch fatigue strength. For these reasons a study has been undertaken to assess the notch dwell fatigue strength of a modern PM disk alloy through spin pit evaluation of a prototypical disk. The first element of this program involves screening potential heat treatments with respect to notch fatigue strength at 1300 F utilizing a conventional notch fatigue specimen with a stress concentration factor (K(sub t)) of 2 and a 90 sec dwell at peak load. The results of this effort are reported in this paper including the downselect of an optimal heat treatment, from a notch fatigue standpoint.

  16. Numerical analysis on solidification process and heat transfer of FGH95 superalloy droplets during PREP

    Institute of Scientific and Technical Information of China (English)

    Huanming Chen; Benfu Hu; Yiwen Zhang; Quanmao Yu; Huiying Li

    2003-01-01

    In order to understand the relation between microstructure of superalloy powders and its solidification progress, the processing parameters are optimized during plasma rotating electrode processing (PREP). It was predicted from the results that the droplet velocities, droplet temperature, and fractional solidification with flight time about FGH95 superalloy droplet have been carried out based on Newtonian heat transfer formulation coupled with the classical heterogeneous nucleation and the specific solidification process. It has been found that the droplet dynamic and thermal behavior is strongly affected by the distribution of droplet diameters,the proportion of cooling atmosphere, but is relatively unaffected by the droplet superheat.

  17. Enhanced Corrosion Resistance of a Transient Liquid Phase Bonded Nickel-Based Superalloy

    Science.gov (United States)

    Adebajo, O. J.; Ojo, O. A.

    2017-01-01

    Electrochemical analysis of corrosion performance of a transient liquid phase (TLP) bonded nickel-based superalloy was performed. The TLP bonding process resulted in significant reduction in corrosion resistance due to the formation of non-equilibrium solidification reaction micro-constituents within the joint region. The corrosion resistance degradation is completely eliminated through a new application of composite interlayer that had been previously considered unusable for joining single-crystal superalloys. The effectiveness of the new approach becomes more pronounced as the severity of environment increases.

  18. Microstructural Investigations and Modelling of Interdiffusion between MCrAlY Coating and IN738 Superalloy

    DEFF Research Database (Denmark)

    Dahl, Kristian Vinter; Hald, John

    2006-01-01

    Interdiffusion at the interface between a Co-36.5Ni-17.5Cr-8Al-0.5Y, MCrAlY coating and the underlying IN738 superalloy was studied in a large matrix of specimens isothermally heat treated for up to 12,000 hours at temperatures 875°C, 925°C or 950°C. Microstructural investigations and calculated...... phase fraction diagrams show that a precipitate free zone forms between the coating and superalloy and grows with time. Measured composition profiles across the interface were compared with modelled results obtained using the finite difference software DICTRA. The simulated results were able...

  19. Effect of Phosphorus on Microstructure and High Temperature Properties of a Cast Ni-base Superalloy

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Effect of phosphorus on the microstructure and high temperature properties of a cast Ni-base superalloy M963 has been investigated. SEM observation and EDS analysis showed that P was mostly enriched in the interdendritic region, and the P-rich phase was formed in the front position of finally solidified eutectics in high P doped alloys. It was found that the P-rich phase, as preferred initiation and propagation site of cracks, could aggravate the fracture process at high temperature in high P doped alloys. Consequently, high P addition would reduce remarkably the ductility and creep life of M963 superalloy at high temperature.

  20. SOLIDIFICATION OF NICKEL-BASED SINGLE CRYSTAL SUPERALLOY BY ELECTRIC FIELD

    Institute of Scientific and Technical Information of China (English)

    Y.S. Yang; X.H. Feng; G.F. Cheng; Y.J. Li; Z.Q. Hu

    2005-01-01

    The crystal growth of a nickel-based single crystal superalloy DD3 was researched via controlled directional solidification under the action of a DC electric field. The cellular or dendrite spacing of the single crystal superalloy is refined and microsegregation of alloying elements Al,Ti, Mo and W, is reduced by the electric field. The electric field decreases the interface stability and reduces the critical growth rate of the cellular-dendritic translation because of Thomson effect and Joule heating. The precipitation of the γ' phase is more uniform and the size of the γ'phase is smaller with the electric field than that without the electric field.

  1. High temperature thermal diffusivity of nickel-based superalloys and intermetallic compounds

    OpenAIRE

    Hazotte, A.; Perrot, B.; Archambault, P

    1993-01-01

    By means of an installation developed in our laboratory, we measured the thermal diffusivity (α) as a function of temperature for several single and polycrystal nickel-based superalloys as well as for different intermetallic compounds with a L12 (Ni3Al, Ni3Si, Ni3Ge, Ni3Fe, Zr3Al, Co3Ti), L10 (TiAl) or B2 (NiAl) structure. In the case of nickel-based superalloys, the experiments pointed out an unexpected but reproductible slope change in the α=f(T) curves at about 750°C, which is not explaine...

  2. An overview of the measurements of thermophysical properties and some results on molten superalloys and semiconductors

    Science.gov (United States)

    Taylor, R. E.

    1993-01-01

    This presentation consists of two parts: comments on the results of measurements on thermophysical properties based on the paper, 'Things Mother Never Taught Me (About Thermophysical Properties of Solids)' and results of thermophysical property measurements on selected solid and molten semiconductors and a proprietary superalloy. The first part may be considered as a tutorial for those involved in using or procuring thermophysical property data. The second part is presented as illustrations of what has been accomplished on molten materials at the Thermophysical Properties Research Laboratory (TPRL). The materials include Ge, PbTe, PbSnTe, HgCdTe and a superalloy.

  3. Lattice of ℤ-module

    Directory of Open Access Journals (Sweden)

    Futa Yuichi

    2016-03-01

    Full Text Available In this article, we formalize the definition of lattice of ℤ-module and its properties in the Mizar system [5].We formally prove that scalar products in lattices are bilinear forms over the field of real numbers ℝ. We also formalize the definitions of positive definite and integral lattices and their properties. Lattice of ℤ-module is necessary for lattice problems, LLL (Lenstra, Lenstra and Lovász base reduction algorithm [14], and cryptographic systems with lattices [15] and coding theory [9].

  4. An Algorithm on Generating Lattice Based on Layered Concept Lattice

    Directory of Open Access Journals (Sweden)

    Zhang Chang-sheng

    2013-08-01

    Full Text Available Concept lattice is an effective tool for data analysis and rule extraction, a bottleneck factor on impacting the applications of concept lattice is how to generate lattice efficiently. In this paper, an algorithm LCLG on generating lattice in batch processing based on layered concept lattice is developed, this algorithm is based on layered concept lattice, the lattice is generated downward layer by layer through concept nodes and provisional nodes in current layer; the concept nodes are found parent-child relationships upward layer by layer, then the Hasse diagram of inter-layer connection is generated; in the generated process of the lattice nodes in each layer, we do the pruning operations dynamically according to relevant properties, and delete some unnecessary nodes, such that the generating speed is improved greatly; the experimental results demonstrate that the proposed algorithm has good performance.

  5. Improved Analysis of Kannan's Shortest Lattice Vector Algorithm

    CERN Document Server

    Hanrot, Guillaume

    2007-01-01

    The security of lattice-based cryptosystems such as NTRU, GGH and Ajtai-Dwork essentially relies upon the intractability of computing a shortest non-zero lattice vector and a closest lattice vector to a given target vector in high dimensions. The best algorithms for these tasks are due to Kannan, and, though remarkably simple, their complexity estimates have not been improved since more than twenty years. Kannan's algorithm for solving the shortest vector problem is in particular crucial in Schnorr's celebrated block reduction algorithm, on which are based the best known attacks against the lattice-based encryption schemes mentioned above. Understanding precisely Kannan's algorithm is of prime importance for providing meaningful key-sizes. In this paper we improve the complexity analyses of Kannan's algorithms and discuss the possibility of improving the underlying enumeration strategy.

  6. The JKJ Lattice

    Science.gov (United States)

    Shigaki, Kenta; Noda, Fumiaki; Yamamoto, Kazami; Machida, Shinji; Molodojentsev, Alexander; Ishi, Yoshihiro

    2002-12-01

    The JKJ high-intensity proton accelerator facility consists of a 400-MeV linac, a 3-GeV 1-MW rapid-cycling synchrotron and a 50-GeV 0.75-MW synchrotron. The lattice and beam dynamics design of the two synchrotrons are reported.

  7. Quantum lattice problems

    NARCIS (Netherlands)

    de Raedt, Hans; von der Linden, W.; Binder, K

    1995-01-01

    In this chapter we review methods currently used to perform Monte Carlo calculations for quantum lattice models. A detailed exposition is given of the formalism underlying the construction of the simulation algorithms. We discuss the fundamental and technical difficulties that are encountered and gi

  8. Measuring on Lattices

    CERN Document Server

    Knuth, Kevin H

    2009-01-01

    Previous derivations of the sum and product rules of probability theory relied on the algebraic properties of Boolean logic. Here they are derived within a more general framework based on lattice theory. The result is a new foundation of probability theory that encompasses and generalizes both the Cox and Kolmogorov formulations. In this picture probability is a bi-valuation defined on a lattice of statements that quantifies the degree to which one statement implies another. The sum rule is a constraint equation that ensures that valuations are assigned so as to not violate associativity of the lattice join and meet. The product rule is much more interesting in that there are actually two product rules: one is a constraint equation arises from associativity of the direct products of lattices, and the other a constraint equation derived from associativity of changes of context. The generality of this formalism enables one to derive the traditionally assumed condition of additivity in measure theory, as well in...

  9. Lattice Multiverse Models

    OpenAIRE

    Williamson, S. Gill

    2010-01-01

    Will the cosmological multiverse, when described mathematically, have easily stated properties that are impossible to prove or disprove using mathematical physics? We explore this question by constructing lattice multiverses which exhibit such behavior even though they are much simpler mathematically than any likely cosmological multiverse.

  10. Phenomenology from lattice QCD

    CERN Document Server

    Lellouch, L P

    2003-01-01

    After a short presentation of lattice QCD and some of its current practical limitations, I review recent progress in applications to phenomenology. Emphasis is placed on heavy-quark masses and on hadronic weak matrix elements relevant for constraining the CKM unitarity triangle. The main numerical results are highlighted in boxes.

  11. Noetherian and Artinian Lattices

    Directory of Open Access Journals (Sweden)

    Derya Keskin Tütüncü

    2012-01-01

    Full Text Available It is proved that if L is a complete modular lattice which is compactly generated, then Rad(L/0 is Artinian if, and only if for every small element a of L, the sublattice a/0 is Artinian if, and only if L satisfies DCC on small elements.

  12. The Effect of Forging Variables on the Supersolvus Heat-Treatment Response of Powder-Metallurgy Nickel-Base Superalloys

    Science.gov (United States)

    2014-12-01

    AFRL-RX-WP-JA-2015-0160 THE EFFECT OF FORGING VARIABLES ON THE SUPERSOLVUS HEAT-TREATMENT RESPONSE OF POWDER-METALLURGY NICKEL -BASE SUPERALLOYS...POWDER-METALLURGY NICKEL - BASE SUPERALLOYS (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62102F 6. AUTHOR...of Powder-Metallurgy Nickel -Base Superalloys S.L. SEMIATIN, J.M. SHANK, A.R. SHIVELEY, W.M. SAURBER, E.F. GAUSSA, and A.L. PILCHAK The effect of

  13. Evaluation of Characteristics of Non-Metallic Inclusions in P/M Ni-Base Superalloy by Automatic Image Analysis

    Institute of Scientific and Technical Information of China (English)

    Li; Xinggang; Ge; Changchun; Shen; Weiping

    2007-01-01

    Non-metallic inclusions,especially the large ones,within P/M Ni-base superalloy have a major influence on fatigue characteristics,but are not directly measurable by routine inspection.In this paper,a method,automatic image analysis,is proposed for estimation of the content,size and amount of non-metallic inclusions in superalloy.The methodology for the practical application of this method is described and the factors affecting the precision of the estimation are discussed.In the experiment,the characteristics of the non-metallic inclusions in Ni-base P/M superalloy are analyzed.

  14. Basis reduction for layered lattices

    NARCIS (Netherlands)

    Torreão Dassen, Erwin

    2011-01-01

    We develop the theory of layered Euclidean spaces and layered lattices. We present algorithms to compute both Gram-Schmidt and reduced bases in this generalized setting. A layered lattice can be seen as lattices where certain directions have infinite weight. It can also be interpre

  15. Time-incremental creep–fatigue damage rule for single crystal Ni-base superalloys

    NARCIS (Netherlands)

    Tinga, T.; Brekelmans, W.A.M.; Geers, M.G.D.

    2009-01-01

    In the present paper a damage model for single crystal Ni-base superalloys is proposed that integrates time-dependent and cyclic damage into a generally applicable time-incremental damage rule. A criterion based on the Orowan stress is introduced to detect slip reversal on the microscopic level and

  16. Recovery of Nickel from Nickel-Based Superalloy Scraps by Utilizing Molten Zinc

    Science.gov (United States)

    Yagi, Ryohei; Okabe, Toru H.

    2017-02-01

    With the purpose of developing a new process for recycling nickel (Ni) directly from superalloy scraps, a fundamental study on the extraction and separation of Ni was carried out using molten zinc (Zn) as the extraction medium. In order to examine the reaction between molten Zn and the Ni-based superalloy, superalloy samples and Zn shots were heated at 1173 K (900 °C) for 6 hours. After heating, the superalloy samples fully reacted with Zn and dissolved in molten Zn. The Zn-alloyed sample obtained by slow cooling consisted of two separated upper and lower phases. In the upper part of the sample, only Zn and the Zn-Ni alloys were found; in the lower part, an intermetallic alloy consisting of refractory metals such as rhenium (Re) and tantalum (Ta) was found. This result shows that Ni and refractory metals contained in the scrap can be separated by utilizing the density differences between the Zn-Ni alloy and the refractory metals in molten Zn. Vacuum treatment of the upper part of the Zn-alloyed sample at 1173 K (900 °C) reduced the concentration of Zn in the sample from 97.0 to 0.4 mass pct. After Zn removal, a Ni alloy containing Ni with a purity of 85.3 to 86.1 mass pct and negligible quantities (scraps without the consumption of Zn or the generation of toxic wastes solutions.

  17. US/Japan Seminar on Superalloys Held at Susono, Japan on 7-11 December 1984.

    Science.gov (United States)

    2014-09-26

    University of Technology) STRENGTH AND PHASE STABILITY OF Ni Al INTERMETALLIC COMPOUNDS -TOWARD ALLOY DESIGN OF SUPERALLOYS- Y. Mishima , T. Suzuki (Tokyo...Kawasaki Heavy Industries, Technical Institute Nishiyama, Yukio Kawasaki Heavy Industries, Technical Institute Tanaka, Shoji Kawasaki Steel, Research...Technology Matsuo, Takashi Tokyo Institute of Technology Mishima , Yoshinao Tokyo Institute of Technology Takeyama, Masao Tokyo Institute of

  18. Freckle Defect Formation near the Casting Interfaces of Directionally Solidified Superalloys

    Directory of Open Access Journals (Sweden)

    Jianping Hong

    2016-11-01

    Full Text Available Freckle defects usually appear on the surface of castings and industrial ingots during the directional solidification process and most of them are located near the interface between the shell mold and superalloys. Ceramic cores create more interfaces in the directionally solidified (DS and single crystal (SX hollow turbine blades. In order to investigate the location of freckle occurrence in superalloys, superalloy CM247 LC was directionally solidified in an industrial-sized Bridgman furnace. Instead of ceramic cores, Alumina tubes were used inside of the casting specimens. It was found that freckles occur not only on the casting external surfaces, but also appear near the internal interfaces between the ceramic core and superalloys. Meanwhile, the size, initial position, and area of freckle were investigated in various diameters of the specimens. The initial position of the freckle chain reduces when the diameter of the rods increase. Freckle area follows a linear relationship in various diameters and the average freckle fraction is 1.1% of cross sectional area of casting specimens. The flow of liquid metal near the interfaces was stronger than that in the interdendritic region in the mushy zone, and explained why freckle tends to occur on the outer or inner surfaces of castings. This new phenomenon suggests that freckles are more likely to occur on the outer or inner surfaces of the hollow turbine blades.

  19. Use of atomic force microscopy to quantify slip irreversibility in a nickel-base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Risbet, M.; Feaugas, X.; Guillemer-Neel, C.; Clavel, M

    2003-09-15

    Atomic force microscopy was used to study the evolution of surface deformation during cyclic loading in a nickel-base superalloy. Cyclic slip irreversibility has been investigated using quantitative evaluation of extrusion heights and inter-band spacing. This approach is applied to formulate a microscopic crack initiation law, compared to a classical Manson-Coffin relationship.

  20. Combustion Synthesis of NiAl and In-situ Joining to Ni-based Superalloy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Combustion synthesis is used as a joining technology to join Ni-based superalloys with in-situ synthesized NiAl filler. The synthesis mechanism is discussed. The microstructure of the joints is investigated and the joint strength is also evaluated by tensile testing.

  1. Cube slip and non-Schmid effects in single crystal Ni-base superalloys

    NARCIS (Netherlands)

    Tinga, T.; Brekelmans, W.A.M.; Geers, M.G.D.

    2010-01-01

    An advanced constitutive model incorporating two specific aspects of Ni-base superalloy deformation behaviour is proposed. Several deformation mechanisms are active in these two-phase materials. In the matrix phase, cube slip plays an important role in the orientation dependence of the material. Mor

  2. Directional coarsening in nickel-base superalloys and its effect on the mechanical properties

    NARCIS (Netherlands)

    Tinga, T.; Brekelmans, W.A.M.; Geers, M.G.D.

    2009-01-01

    During high temperature loading, the regular microstructure of nickel-base superalloys consisting of a γ-matrix (Ni) containing a large volume fraction of γ′-particles (Ni3Al) degrades. The cubic precipitates coarsen and elongate in a direction normal to the applied stress in a process called raftin

  3. Alloy Design Challenge: Development of Low Density Superalloys for Turbine Blade Applications

    Science.gov (United States)

    MacKay, Rebecca A.; Gabb, Timothy P.; Smialek, James L.; Nathal, Michael V.

    2009-01-01

    New low density single crystal (LDS) alloys have been developed for turbine blade applications, which have the potential for significant improvements in the thrust to weight ratio over current production alloys. An innovative alloying strategy was identified to achieve high temperature creep resistance, alloy density reductions, microstructural stability, and cyclic oxidation resistance. The approach relies on the use of molybdenum (Mo) as a potent solid solution strengthener for the nickel (Ni)-base superalloy; Mo has a density much closer to Ni than other refractory elements, such as rhenium (Re) or tungsten (W). A host of testing and microstructural examinations was conducted on the superalloy single crystals, including creep rupture testing, microstructural stability, cyclic oxidation, and hot corrosion. The paper will provide an overview of the single crystal properties that were generated in this new superalloy design space. The paper will also demonstrate the feasibility of this innovative approach of low density single crystal superalloy design. It will be shown that the best LDS alloy possesses the best attributes of three generations of single crystal alloys: the low density of first-generation single crystal alloys, the excellent oxidation resistance of second-generation single crystal alloys, and a creep strength which exceeds that of second and third generation alloys.

  4. Mechanisms of High Temperature/Low Stress Creep of Ni-Based Superalloy Single Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Michael J. Mills

    2009-03-05

    Cast nickel-based superalloys are used for blades in land-based, energy conversion and powerplant applications, as well as in aircraft gas turbines operating at temperatures up to 1100 C, where creep is one of the life-limiting factors. Creep of superalloy single crystals has been extensively studied over the last several decades. Surprisingly, only recently has work focused specifically on the dislocation mechanisms that govern high temperature and low stress creep. Nevertheless, the perpetual goal of better engine efficiency demands that the creep mechanisms operative in this regime be fully understood in order to develop alloys and microstructures with improved high temperature capability. At present, the micro-mechanisms controlling creep before and after rafting (the microstructure evolution typical of high temperature creep) has occurred have yet to be identified and modeled, particularly for [001] oriented single crystals. This crystal orientation is most interesting technologically since it exhibits the highest creep strength. The major goal of the program entitled ''Mechanisms of High Temperature/Low Stress Creep of Ni-Based Superalloy Single Crystals'' (DOE Grant DE-FG02-04ER46137) has been to elucidate these creep mechanisms in cast nickel-based superalloys. We have utilized a combination of detailed microstructure and dislocation substructure analysis combined with the development of a novel phase-field model for microstructure evolution.

  5. Refractory porcelain enamel passive-thermal-control coating for high-temperature superalloys

    Science.gov (United States)

    Levin, H.; Auker, B. H.; Gardos, M. N.

    1973-01-01

    Study was conducted to match thermal expansion coefficients thereby preventing enamels from cracking. Report discusses various enamel coatings that are applied to two different high-temperature superalloys. Study may be of interest to manufacturers of chemical equipment, furnaces, and metal components intended for high-temperature applications.

  6. Effect of Yttrium on High Temperature Oxidation Resistance of a Directionally Solidified Superalloy

    Institute of Scientific and Technical Information of China (English)

    宋立国; 李树索; 郑运荣; 韩雅芳

    2004-01-01

    The effect of rare earth element yttrium on the high temperature oxidation resistance of a directionally solidified Ni-base superalloy was studied with scanning electron microscopy(SEM), energy dispersive spectrum(EDS)and X-ray diffraction(XRD)techniques. The results show that the oxidation resistance of the alloy is substantially improved by adding proper amount of yttrium.

  7. Design and characterization of novel precipitation hardenable high Cr Ni-based superalloys

    DEFF Research Database (Denmark)

    Bihlet, Uffe; Dahl, Kristian Vinter; Somers, Marcel A. J.

    2012-01-01

    Among the Ni-based superalloys, Alloy 718 stands apart with the ability to be precipitation hardened after welding, by the slow formation of nano-scale γ’’ (Ni3Nb) particles. This slow formation gives it a very low crack susceptibility, which has made it widely applied since its introduction...

  8. A study of microstructural characteristics of Ni-based superalloys at high temperatures

    Science.gov (United States)

    Lal, Ravindra B.; Aggarwal, M. D.

    1990-01-01

    The microstructural characteristics of the Ni-based superalloy MAR-M245(Hf) which is used in manufacturing the components of the Space Shuttle main engine are studied. These superalloys need optimum heat treatment to get the best results. To find out the optimum heat treatment, the techniques of differential thermal analysis (DTA) and the optical photomicrographs were utilized. In the first phase, the existing experimental equipment like cutting, grinding/polishing machines and metallurgical microscope were set up to cut/polish and take the photomicrographs. In the beginning of the project a Perkin Elmer differential thermal analyzer DTA1700 along with a temperature programmed and the needed computer interface was procured and made operational. In the second year a Leitz Metallux-3 hot state research microscope was also procured and installed for in-situ observation of the superalloy samples. The hot stage when tested for the first time alloyed the thermocouple with the Tantalum heating element and has now been installed. Samples of MAR-M246(Hf), MAR-M247, Waspaloy, Udimet-41, CMSX-3, and CMSX-3 (Polycrystalline and single crystals) were studied using a differential thermal analyzer and the results are reported. Photomicrographs of the Ni-based superalloy MAR-M246 (Hf) were recorded before and after heat treatment at certain temperatures. More heat treatments need to be done before a final inference can be reached.

  9. Investigation of nickel- and cobalt-based superalloys with protective coatings

    Science.gov (United States)

    Veksler, Yu. G.; Mal'tseva, L. A.; Pastukhov, M. V.

    2015-03-01

    The structure and composition of the surface layers of MAR-M247 and MAR-M509 superalloys are studied after the formation of protective coatings by gas-circulation aluminizing and a high-energy ion-plasma technology.

  10. Modeling cast IN-738 superalloy gas tungsten arc welds

    Energy Technology Data Exchange (ETDEWEB)

    Bonifaz, E.A. [Department of Mechanical and Manufacturing Engineering, University of Manitoba, E2-327F EITC, Winnipeg, Man., R3T 5V6 (Canada); Universidad San Francisco de Quito, Casilla Postal: 17-12-841 Circulo de Cumbaya, Quito (Ecuador)], E-mail: bonifaz@cc.umanitoba.ca; Richards, N.L. [Department of Mechanical and Manufacturing Engineering, University of Manitoba, E2-327F EITC, Winnipeg, Man., R3T 5V6 (Canada)], E-mail: nrichar@cc.umanitoba.ca

    2009-04-15

    A three-dimensional finite-element thermal model has been developed to generate weld profiles, and to analyze transient heat flow, thermal gradients and thermal cycles in cast IN-738 superalloy gas tungsten arc welds. Outputs of the model (cooling rates, the thermal gradient G and the growth rate R) were used to describe solidification structures found around the weld pool for three different welding speeds at constant heat input. Calculations around the weld pool indicate that the cooling rate increases from the fusion line to the centerline at all welding speeds. It was also observed that the cooling rate (G x R) and the ratio G/R fall with welding speed. For instance, as the welding speed is increased, the cooling rates at the centerline, fusion line and penetration depth decrease. Moreover, it was observed that as the power and welding speed both increase (but keeping the heat input constant), the weld pool becomes wider and more elongated, shifting from circular to elliptical shaped. The calculations were performed using ABAQUS FE code on the basis of a time-increment Lagrangian formulation. The heat source represented by a moving Gaussian power density distribution is applied over the top surface of the specimen during a period of time that depends on the welding speed. Temperature-dependent material properties and the effect of forced convection due to the flow of the shielding gas are included in the model. Numerically predicted sizes of the melt-pool zone and dendrite secondary arm spacing induced by the gas tungsten arc welding process are also given.

  11. Deformation modeling and constitutive modeling for anisotropic superalloys

    Science.gov (United States)

    Milligan, Walter W.; Antolovich, Stephen D.

    1989-01-01

    A study of deformation mechanisms in the single crystal superalloy PWA 1480 was conducted. Monotonic and cyclic tests were conducted from 20 to 1093 C. Both (001) and near-(123) crystals were tested, at strain rates of 0.5 and 50 percent/minute. The deformation behavior could be grouped into two temperature regimes: low temperatures, below 760 C; and high temperatures, above 820 to 950 C depending on the strain rate. At low temperatures, the mechanical behavior was very anisotropic. An orientation dependent CRSS, a tension-compression asymmetry, and anisotropic strain hardening were all observed. The material was deformed by planar octahedral slip. The anisotropic properties were correlated with the ease of cube cross-slip, as well as the number of active slip systems. At high temperatures, the material was isotropic, and deformed by homogeneous gamma by-pass. It was found that the temperature dependence of the formation of superlattice-intrinsic stacking faults was responsible for the local minimum in the CRSS of this alloy at 400 C. It was proposed that the cube cross-slip process must be reversible. This was used to explain the reversible tension-compression asymmetry, and was used to study models of cross-slip. As a result, the cross-slip model proposed by Paidar, Pope and Vitek was found to be consistent with the proposed slip reversibility. The results were related to anisotropic viscoplastic constitutive models. The model proposed by Walter and Jordan was found to be capable of modeling all aspects of the material anisotropy. Temperature and strain rate boundaries for the model were proposed, and guidelines for numerical experiments were proposed.

  12. Microstructural aspects of fatigue in Ni-base superalloys.

    Science.gov (United States)

    Antolovich, Stephen D

    2015-03-28

    Nickel-base superalloys are primarily used as components in jet engines and land-based turbines. While compositionally complex, they are microstructurally simple, consisting of small (50-1000 nm diameter), ordered, coherent Ni(3)(Al,Ti)-type L1(2) or Ni(3)Nb-type DO(22) precipitates (called γ(') and γ(''), respectively) embedded in an FCC substitutional solid solution consisting primarily of Ni and other elements which confer desired properties depending upon the application. The grain size may vary from as small as 2 μm for powder metallurgy alloys used in discs to single crystals the actual size of the component for turbine blades. The fatigue behaviour depends upon the microstructure, deformation mode, environment and cycle time. In many cases, it can be controlled or modified through small changes in composition which may dramatically change the mechanism of damage accumulation and the fatigue life. In this paper, the fundamental microstructural, compositional, environmental and deformation mode factors which affect fatigue behaviour are critically reviewed. Connections are made across a range of studies to provide more insight. Modern approaches are pointed out in which the wealth of available microstructural, deformation and damage information is used for computerized life prediction. The paper ends with a discussion of the very important and highly practical subject of thermo-mechanical fatigue (TMF). It is shown that physics-based modelling leads to significantly improved life prediction. Suggestions are made for moving forward on the critical subject of TMF life prediction in notched components. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  13. Fabrication and Optimization of Ni Superalloy Inconel 600 Microtruss Materials

    Science.gov (United States)

    Devatha Venkatesh, Balaji

    Microtruss materials are multifunctional cellular hybrids composed of an interconnected arrangement of internal struts that can offer enhanced strength and stiffness at low densities. This study looks at the potential of Ni-based superalloys as microtruss materials. The potential of using the in-situ plastic strain imparted during stretch forming to grain boundary engineer the internal struts of Inconel 600 (IN600) cellular hybrids was also explored. In order to examine this question, a combination of experimental and finite element (FE) methods were employed. The non-uniform plastic deformation imparted to the microtruss struts during fabrication was modeled by FE and the local changes in grain boundary character in the fabricated trusses were mapped by electron backscattered diffraction. This study also examined the distribution of plastic strain over the microtruss architecture. A mechanical press with various pin geometries was employed to experimentally validate the FE models. Standard pin geometry results in substantially non-uniform plastic strain, which limits the maximum formability of the starting sheet material. Importantly, pins designed with tapers and spheres were shown to impart plastic strain along the entire length of the microtruss. This opened up possibility of new design strategies for facilitating grain boundary engineering over the entire truss. It may also present opportunities for enhancing the energy absorption performance of microtruss materials. Finally, this study examined the mechanical properties of IN600 microtrusses, in particular focusing on the significance of strut end constraints in determining the overall mechanical performance. While it is straightforward to analytically determine the inelastic buckling resistance of plastically deformed struts, there is no simple way to determine the rotational end constraint of the struts deformed to varying truss angles. It was seen that end constraint rigidity k could be determined using a

  14. Thermomechanical fatigue crack growth in a cast polycrystalline superalloy

    Directory of Open Access Journals (Sweden)

    Moverare Johan J.

    2014-01-01

    Full Text Available Thermomechanical fatigue (TMF crack growth testing has been performed on the polycrystalline superalloy IN792. All tests were conducted in mechanical strain control in the temperature range between 100 and 750 °C. The influence of in-phase (IP and out-of-phase (OP TMF cycles was investigated as well as the influence of applying extended dwell times (up to 6 hours at the maximum temperature. The crack growth rates were also evaluated based on linear elastic fracture mechanics and described as a function of the stress intensity factor KI. Without dwell time at the maximum temperature, the crack growth rates are generally higher for the OP-TMF cycle compared to the IP-TMF cycle, when equivalent nominal strain ranges are compared. However, due to the fact that the tests were conducted in mechanical strain control, the stress response is very different for the IP and OP cycles. Also the crack closure level differs significantly between the cycle types. By taking the stress response into account and comparing the crack growth rates for equivalent effective stress intensity factor rages ΔKeff defined as Kmax − Kclosure, very similar crack growth rates were actually noticed independent of whether an IP or OP cycle were used. While the introduction of a 6 hour dwell time significantly increased the crack growth rates for the IP-TMF cycle, a decrease in crack growth rates versus ΔKeff were actually seen for the OP-TMF cycle. The fracture behaviour during the different test conditions has been investigated using scanning electron microscopy.

  15. Microstructural analysis of weld cracking in 718 Plus superalloy

    Science.gov (United States)

    Vishwakarma, Krutika

    Allvac 718RTM PLUS(TM) (718 Plus) is a new Ni-base superalloy developed to be used in land and aero gas turbine applications. 718 Plus was developed to have high temperature properties superior to its baseline superalloy Inconel 718, while maintaining its workability. Besides its high temperature properties superior to Inconel 718, limited information exists about its physical metallurgy or weldability. This project studied the microstructure and electron beam welding response of this new superalloy in two selected pre-weld heat treated conditions. To further understand the effect of minor alloying elements on its weldability, two versions of 718 Plus with varying concentrations of boron and phosphorus, HC 49 with higher B and P and HC 20 with normal B and P, were also studied. Finally, the weldability of 718 Plus alloys was compared to that of Inconel 718 and Waspaloy under similar welding conditions. Hot rolled wrought plates of Inconel 718, Waspaloy and 718 Plus alloys were supplied by ALLVAC Inc. 12.7 mm x 12.7 mm x 101.6 mm sections were cut normal to the rolling direction of the plates and were subjected to their recommended respective solution heat treatments, viz., 950°C for 1 hour for 718 Plus alloys and Inconel 718 and 1020°C for 1 hour for Waspaloy. 718 Plus alloys and Inconel 718 were also examined after another solution heat treatment at 1050°C for 1 hour. All the heat treatments were followed by water quenching. Thorough microstructural characterization before and after welding was carried out using optical microscopy, analytical scanning electron microscopy, electron microprobe analysis and analytical transmission electron microscopy. In addition, Secondary Ion Mass Spectrometer (SIMS) was used to study the grain boundary segregation in the two 718 Plus alloys. Interestingly, the microstructure of 718 Plus alloy, in the heat treated conditions it was studied, was very similar to that of Inconel 718 despite of the considerable difference in their

  16. Introduction to lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, R.

    1998-12-31

    The goal of the lectures on lattice QCD (LQCD) is to provide an overview of both the technical issues and the progress made so far in obtaining phenomenologically useful numbers. The lectures consist of three parts. The author`s charter is to provide an introduction to LQCD and outline the scope of LQCD calculations. In the second set of lectures, Guido Martinelli will discuss the progress they have made so far in obtaining results, and their impact on Standard Model phenomenology. Finally, Martin Luescher will discuss the topical subjects of chiral symmetry, improved formulation of lattice QCD, and the impact these improvements will have on the quality of results expected from the next generation of simulations.

  17. Lattice Quantum Chromodynamics

    Science.gov (United States)

    Sachrajda, C. T.

    2016-10-01

    I review the the application of the lattice formulation of QCD and large-scale numerical simulations to the evaluation of non-perturbative hadronic effects in Standard Model Phenomenology. I present an introduction to the elements of the calculations and discuss the limitations both in the range of quantities which can be studied and in the precision of the results. I focus particularly on the extraction of the QCD parameters, i.e. the quark masses and the strong coupling constant, and on important quantities in flavour physics. Lattice QCD is playing a central role in quantifying the hadronic effects necessary for the development of precision flavour physics and its use in exploring the limits of the Standard Model and in searches for inconsistencies which would signal the presence of new physics.

  18. Lattices of dielectric resonators

    CERN Document Server

    Trubin, Alexander

    2016-01-01

    This book provides the analytical theory of complex systems composed of a large number of high-Q dielectric resonators. Spherical and cylindrical dielectric resonators with inferior and also whispering gallery oscillations allocated in various lattices are considered. A new approach to S-matrix parameter calculations based on perturbation theory of Maxwell equations, developed for a number of high-Q dielectric bodies, is introduced. All physical relationships are obtained in analytical form and are suitable for further computations. Essential attention is given to a new unified formalism of the description of scattering processes. The general scattering task for coupled eigen oscillations of the whole system of dielectric resonators is described. The equations for the  expansion coefficients are explained in an applicable way. The temporal Green functions for the dielectric resonator are presented. The scattering process of short pulses in dielectric filter structures, dielectric antennas  and lattices of d...

  19. Fractional lattice charge transport

    Science.gov (United States)

    Flach, Sergej; Khomeriki, Ramaz

    2017-01-01

    We consider the dynamics of noninteracting quantum particles on a square lattice in the presence of a magnetic flux α and a dc electric field E oriented along the lattice diagonal. In general, the adiabatic dynamics will be characterized by Bloch oscillations in the electrical field direction and dispersive ballistic transport in the perpendicular direction. For rational values of α and a corresponding discrete set of values of E(α) vanishing gaps in the spectrum induce a fractionalization of the charge in the perpendicular direction - while left movers are still performing dispersive ballistic transport, the complementary fraction of right movers is propagating in a dispersionless relativistic manner in the opposite direction. Generalizations and the possible probing of the effect with atomic Bose-Einstein condensates and photonic networks are discussed. Zak phase of respective band associated with gap closing regime has been computed and it is found converging to π/2 value. PMID:28102302

  20. Lattice QCD for Cosmology

    CERN Document Server

    Borsanyi, Sz; Kampert, K H; Katz, S D; Kawanai, T; Kovacs, T G; Mages, S W; Pasztor, A; Pittler, F; Redondo, J; Ringwald, A; Szabo, K K

    2016-01-01

    We present a full result for the equation of state (EoS) in 2+1+1 (up/down, strange and charm quarks are present) flavour lattice QCD. We extend this analysis and give the equation of state in 2+1+1+1 flavour QCD. In order to describe the evolution of the universe from temperatures several hundreds of GeV to several tens of MeV we also include the known effects of the electroweak theory and give the effective degree of freedoms. As another application of lattice QCD we calculate the topological susceptibility (chi) up to the few GeV temperature region. These two results, EoS and chi, can be used to predict the dark matter axion's mass in the post-inflation scenario and/or give the relationship between the axion's mass and the universal axionic angle, which acts as a initial condition of our universe.

  1. Solitons in nonlinear lattices

    CERN Document Server

    Kartashov, Yaroslav V; Torner, Lluis

    2010-01-01

    This article offers a comprehensive survey of results obtained for solitons and complex nonlinear wave patterns supported by purely nonlinear lattices (NLs), which represent a spatially periodic modulation of the local strength and sign of the nonlinearity, and their combinations with linear lattices. A majority of the results obtained, thus far, in this field and reviewed in this article are theoretical. Nevertheless, relevant experimental settings are surveyed too, with emphasis on perspectives for implementation of the theoretical predictions in the experiment. Physical systems discussed in the review belong to the realms of nonlinear optics (including artificial optical media, such as photonic crystals, and plasmonics) and Bose-Einstein condensation (BEC). The solitons are considered in one, two, and three dimensions (1D, 2D, and 3D). Basic properties of the solitons presented in the review are their existence, stability, and mobility. Although the field is still far from completion, general conclusions c...

  2. Parametric lattice Boltzmann method

    Science.gov (United States)

    Shim, Jae Wan

    2017-06-01

    The discretized equilibrium distributions of the lattice Boltzmann method are presented by using the coefficients of the Lagrange interpolating polynomials that pass through the points related to discrete velocities and using moments of the Maxwell-Boltzmann distribution. The ranges of flow velocity and temperature providing positive valued distributions vary with regulating discrete velocities as parameters. New isothermal and thermal compressible models are proposed for flows of the level of the isothermal and thermal compressible Navier-Stokes equations. Thermal compressible shock tube flows are simulated by only five on-lattice discrete velocities. Two-dimensional isothermal and thermal vortices provoked by the Kelvin-Helmholtz instability are simulated by the parametric models.

  3. Varieties of lattices

    CERN Document Server

    Jipsen, Peter

    1992-01-01

    The study of lattice varieties is a field that has experienced rapid growth in the last 30 years, but many of the interesting and deep results discovered in that period have so far only appeared in research papers. The aim of this monograph is to present the main results about modular and nonmodular varieties, equational bases and the amalgamation property in a uniform way. The first chapter covers preliminaries that make the material accessible to anyone who has had an introductory course in universal algebra. Each subsequent chapter begins with a short historical introduction which sites the original references and then presents the results with complete proofs (in nearly all cases). Numerous diagrams illustrate the beauty of lattice theory and aid in the visualization of many proofs. An extensive index and bibliography also make the monograph a useful reference work.

  4. Lattice Quantum Chromodynamics

    CERN Document Server

    Sachrajda, C T

    2016-01-01

    I review the the application of the lattice formulation of QCD and large-scale numerical simulations to the evaluation of non-perturbative hadronic effects in Standard Model Phenomenology. I present an introduction to the elements of the calculations and discuss the limitations both in the range of quantities which can be studied and in the precision of the results. I focus particularly on the extraction of the QCD parameters, i.e. the quark masses and the strong coupling constant, and on important quantities in flavour physics. Lattice QCD is playing a central role in quantifying the hadronic effects necessary for the development of precision flavour physics and its use in exploring the limits of the Standard Model and in searches for inconsistencies which would signal the presence of new physics.

  5. International Lattice Data Grid

    CERN Document Server

    Davies, C T H; Kenway, R D; Maynard, C M

    2002-01-01

    We propose the co-ordination of lattice QCD grid developments in different countries to allow transparent exchange of gauge configurations in future, should participants wish to do so. We describe briefly UKQCD's XML schema for labelling and cataloguing the data. A meeting to further develop these ideas will be held in Edinburgh on 19/20 December 2002, and will be available over AccessGrid.

  6. Weakly deformed soliton lattices

    Energy Technology Data Exchange (ETDEWEB)

    Dubrovin, B. (Moskovskij Gosudarstvennyj Univ., Moscow (USSR). Dept. of Mechanics and Mathematics)

    1990-12-01

    In this lecture the author discusses periodic and quasiperiodic solutions of nonlinear evolution equations of phi{sub t}=K (phi, phi{sub x},..., phi{sup (n)}), the so-called soliton lattices. After introducing the theory of integrable systems of hydrodynamic type he discusses their Hamiltonian formalism, i.e. the theory of Poisson brackets of hydrodynamic type. Then he describes the application of algebraic geometry to the effective integration of such equations. (HSI).

  7. Development of advanced P/M Ni-base superalloys for turbine disks

    Directory of Open Access Journals (Sweden)

    Garibov Genrikh S.

    2014-01-01

    Full Text Available In the process of evolution of powder metallurgy in Russia the task permanently formulated was the following: to improve strength properties of P/M superalloys without application of additional complex HIPed blanks deformation operation. On the other hand development of a turbine disk material structure to ensure an improvement in aircraft engine performance requires the use of special HIP and heat treatment conditions. To ensure maximum strength properties of disk materials it is necessary to form a structure which would have optimum size of solid solution grains, γ′-phases and carbides. Along with that heating of the material up to a temperature determined by solvus of an alloy ensures a stable and reproducible level of mechanical properties of the disks. The above-said can be illustrated by successful mastering of new complex-alloyed VVP-class superalloys with the use of powder size − 100 μm. Application of special HIP and heat treatment conditions for these superalloys to obtain the desired grain size and the strengthening γ′-phase precipitates allowed a noticeable improvement in ultimate tensile strength and yield strength up to ≥1600 MPa and ≥1200 MPa respectively. 100 hrs rupture strength at 650 ∘C and 750 ∘C was improved up to 1140 MPa and 750 MPa respectively. P/M VVP nickel-base superalloys offer higher characteristics in comparison with many superalloys designed for the same purposes. HIPed disc compacts manufactured from PREP-powder have a homogeneous micro- and macrostructure, a stable level of mechanical properties.

  8. New knowledge about 'white spots' in superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Jackman, L.A. (Teledyne Allvac, Monroe, N.C. (United States)); Maurer, G.E. (Special Metals Corp., New Hartford, N.Y. (United States)); Widge, S. (Carpenter Technology Corp., Reading, PA (United States))

    1993-05-01

    In April 1991, the first in a series of workshops was held to discuss ways in which the gas turbine industry could better understand defects in nickel-base superalloys. The group's primary objective was to better define, and expand knowledge about, segregation in superalloys such as Alloy 718 and Waspaloy,with emphasis on light-etching areas referred to as solute-lean defects or 'white spots'. This 'White Spots Committee' formed four subcommittees to focus efforts on classification, inspection, mechanisms, and mechanical properties. Completion of the tasks that these subcommittees have undertaken should greatly improve the gas turbine industry's understanding of the physical and mechanical nature of white spots. The primary purpose of this article is to formalize the characterization and classification of white spots in high-strength superalloys so that the metallurgical community can begin to use a common vocabulary when referring to them. An overview of formation mechanisms is presented along with a brief description of detection methods. Also discussed are preliminary test results, which should help shed light on the effects of solute-lean microstructures on tensile and fatigue properties. Although white spots are not limited to any single superalloy or class of superalloy, Alloy 718 is emphasized because it is so widely used, and because its relatively large solidus-liquidus temperature interval ([approximately]75 C, 135 F) and high niobium content ([approximately]5.3% Nb) make it prone to segregation. Three distinct types of white spots have been identified and named by the committee: discrete, dendritic, and solidification white spots.

  9. Solid solution strengthening and diffusion in nickel- and cobalt-based superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, Hamad ur

    2016-07-01

    Nickel and cobalt-based superalloys with a γ-γ{sup '} microstructure are known for their excellent creep resistance at high temperatures. Their microstructure is engineered using different alloying elements, that partition either to the fcc γ matrix or to the ordered γ{sup '} phase. In the present work the effect of alloying elements on their segregation behaviour in nickel-based superalloys, diffusion in cobalt-based superalloys and the temperature dependent solid solution strengthening in nickel-based alloys is investigated. The effect of dendritic segregation on the local mechanical properties of individual phases in the as-cast, heat treated and creep deformed state of a nickel-based superalloy is investigated. The local chemical composition is characterized using Electron Probe Micro Analysis and then correlated with the mechanical properties of individual phases using nanoindentation. Furthermore, the temperature dependant solid solution hardening contribution of Ta, W and Re towards fcc nickel is studied. The room temperature hardening is determined by a diffusion couple approach using nanoindentation and energy dispersive X-ray analysis for relating hardness to the chemical composition. The high temperature properties are determined using compression strain rate jump tests. The results show that at lower temperatures, the solute size is prevalent and the elements with the largest size difference with nickel, induce the greatest hardening consistent with a classical solid solution strengthening theory. At higher temperatures, the solutes interact with the dislocations such that the slowest diffusing solute poses maximal resistance to dislocation glide and climb. Lastly, the diffusion of different technically relevant solutes in fcc cobalt is investigated using diffusion couples. The results show that the large atoms diffuse faster in cobalt-based superalloys similar to their nickel-based counterparts.

  10. Crystallographic Lattice Boltzmann Method

    Science.gov (United States)

    Namburi, Manjusha; Krithivasan, Siddharth; Ansumali, Santosh

    2016-01-01

    Current approaches to Direct Numerical Simulation (DNS) are computationally quite expensive for most realistic scientific and engineering applications of Fluid Dynamics such as automobiles or atmospheric flows. The Lattice Boltzmann Method (LBM), with its simplified kinetic descriptions, has emerged as an important tool for simulating hydrodynamics. In a heterogeneous computing environment, it is often preferred due to its flexibility and better parallel scaling. However, direct simulation of realistic applications, without the use of turbulence models, remains a distant dream even with highly efficient methods such as LBM. In LBM, a fictitious lattice with suitable isotropy in the velocity space is considered to recover Navier-Stokes hydrodynamics in macroscopic limit. The same lattice is mapped onto a cartesian grid for spatial discretization of the kinetic equation. In this paper, we present an inverted argument of the LBM, by making spatial discretization as the central theme. We argue that the optimal spatial discretization for LBM is a Body Centered Cubic (BCC) arrangement of grid points. We illustrate an order-of-magnitude gain in efficiency for LBM and thus a significant progress towards feasibility of DNS for realistic flows. PMID:27251098

  11. Topological Lattice Actions

    CERN Document Server

    Bietenholz, W; Pepe, M; Wiese, U -J

    2010-01-01

    We consider lattice field theories with topological actions, which are invariant against small deformations of the fields. Some of these actions have infinite barriers separating different topological sectors. Topological actions do not have the correct classical continuum limit and they cannot be treated using perturbation theory, but they still yield the correct quantum continuum limit. To show this, we present analytic studies of the 1-d O(2) and O(3) model, as well as Monte Carlo simulations of the 2-d O(3) model using topological lattice actions. Some topological actions obey and others violate a lattice Schwarz inequality between the action and the topological charge $Q$. Irrespective of this, in the 2-d O(3) model the topological susceptibility $\\chi_t = \\l/V$ is logarithmically divergent in the continuum limit. Still, at non-zero distance the correlator of the topological charge density has a finite continuum limit which is consistent with analytic predictions. Our study shows explicitly that some cla...

  12. Robots and lattice automata

    CERN Document Server

    Adamatzky, Andrew

    2015-01-01

    The book gives a comprehensive overview of the state-of-the-art research and engineering in theory and application of Lattice Automata in design and control of autonomous Robots. Automata and robots share the same notional meaning. Automata (originated from the latinization of the Greek word “αυτόματον”) as self-operating autonomous machines invented from ancient years can be easily considered the first steps of robotic-like efforts. Automata are mathematical models of Robots and also they are integral parts of robotic control systems. A Lattice Automaton is a regular array or a collective of finite state machines, or automata. The Automata update their states by the same rules depending on states of their immediate neighbours. In the context of this book, Lattice Automata are used in developing modular reconfigurable robotic systems, path planning and map exploration for robots, as robot controllers, synchronisation of robot collectives, robot vision, parallel robotic actuators. All chapters are...

  13. Hadroquarkonium from lattice QCD

    Science.gov (United States)

    Alberti, Maurizio; Bali, Gunnar S.; Collins, Sara; Knechtli, Francesco; Moir, Graham; Söldner, Wolfgang

    2017-04-01

    The hadroquarkonium picture [S. Dubynskiy and M. B. Voloshin, Phys. Lett. B 666, 344 (2008), 10.1016/j.physletb.2008.07.086] provides one possible interpretation for the pentaquark candidates with hidden charm, recently reported by the LHCb Collaboration, as well as for some of the charmoniumlike "X , Y , Z " states. In this picture, a heavy quarkonium core resides within a light hadron giving rise to four- or five-quark/antiquark bound states. We test this scenario in the heavy quark limit by investigating the modification of the potential between a static quark-antiquark pair induced by the presence of a hadron. Our lattice QCD simulations are performed on a Coordinated Lattice Simulations (CLS) ensemble with Nf=2 +1 flavors of nonperturbatively improved Wilson quarks at a pion mass of about 223 MeV and a lattice spacing of about a =0.0854 fm . We study the static potential in the presence of a variety of light mesons as well as of octet and decuplet baryons. In all these cases, the resulting configurations are favored energetically. The associated binding energies between the quarkonium in the heavy quark limit and the light hadron are found to be smaller than a few MeV, similar in strength to deuterium binding. It needs to be seen if the small attraction survives in the infinite volume limit and supports bound states or resonances.

  14. Digital lattice gauge theories

    Science.gov (United States)

    Zohar, Erez; Farace, Alessandro; Reznik, Benni; Cirac, J. Ignacio

    2017-02-01

    We propose a general scheme for a digital construction of lattice gauge theories with dynamical fermions. In this method, the four-body interactions arising in models with 2 +1 dimensions and higher are obtained stroboscopically, through a sequence of two-body interactions with ancillary degrees of freedom. This yields stronger interactions than the ones obtained through perturbative methods, as typically done in previous proposals, and removes an important bottleneck in the road towards experimental realizations. The scheme applies to generic gauge theories with Lie or finite symmetry groups, both Abelian and non-Abelian. As a concrete example, we present the construction of a digital quantum simulator for a Z3 lattice gauge theory with dynamical fermionic matter in 2 +1 dimensions, using ultracold atoms in optical lattices, involving three atomic species, representing the matter, gauge, and auxiliary degrees of freedom, that are separated in three different layers. By moving the ancilla atoms with a proper sequence of steps, we show how we can obtain the desired evolution in a clean, controlled way.

  15. A Mechanical Lattice Aid for Crystallography Teaching.

    Science.gov (United States)

    Amezcua-Lopez, J.; Cordero-Borboa, A. E.

    1988-01-01

    Introduces a 3-dimensional mechanical lattice with adjustable telescoping mechanisms. Discusses the crystalline state, the 14 Bravais lattices, operational principles of the mechanical lattice, construction methods, and demonstrations in classroom. Provides lattice diagrams, schemes of the lattice, and various pictures of the lattice. (YP)

  16. Kenneth Wilson and lattice QCD

    CERN Document Server

    Ukawa, Akira

    2015-01-01

    We discuss the physics and computation of lattice QCD, a space-time lattice formulation of quantum chromodynamics, and Kenneth Wilson's seminal role in its development. We start with the fundamental issue of confinement of quarks in the theory of the strong interactions, and discuss how lattice QCD provides a framework for understanding this phenomenon. A conceptual issue with lattice QCD is a conflict of space-time lattice with chiral symmetry of quarks. We discuss how this problem is resolved. Since lattice QCD is a non-linear quantum dynamical system with infinite degrees of freedom, quantities which are analytically calculable are limited. On the other hand, it provides an ideal case of massively parallel numerical computations. We review the long and distinguished history of parallel-architecture supercomputers designed and built for lattice QCD. We discuss algorithmic developments, in particular the difficulties posed by the fermionic nature of quarks, and their resolution. The triad of efforts toward b...

  17. Characterization and Modeling of Residual Stress and Cold Work Evolution in PM Nickel Base Disk Superalloy Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Powder metal (PM) superalloys used for critical compressor and turbine disk applications are prone to fatigue failures in stress concentration features such as holes...

  18. Structure and composition of higher-rhenium-content superalloy based on La-alloyed Ni-Al-Cr

    Energy Technology Data Exchange (ETDEWEB)

    Kozlov, Eduard V.; Koneva, Nina A. [Tomsk State University of Architecture and Building, Tomsk, 634003 (Russian Federation); Nikonenko, Elena L., E-mail: vilatomsk@mail.ru [Tomsk State University of Architecture and Building, Tomsk, 634003 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Popova, Natalya A.; Fedorischeva, Marina V. [Tomsk State University of Architecture and Building, Tomsk, 634003 (Russian Federation); Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation)

    2015-10-27

    The paper presents the transmission and scanning electronic microscope investigations of Ni-Al-Cr superalloy alloyed with additional Re and La elements. This superalloy is obtained by a directional solidification method. It is shown that such additional elements as Re and La result in formation of new phases in Ni-Al-Cr accompanied by considerable modifications of quasi-cuboid structure in its γ’-phase.

  19. Ultrasound guided supraclavicular block.

    LENUS (Irish Health Repository)

    Hanumanthaiah, Deepak

    2013-09-01

    Ultrasound guided regional anaesthesia is becoming increasingly popular. The supraclavicular block has been transformed by ultrasound guidance into a potentially safe superficial block. We reviewed the techniques of performing supraclavicular block with special focus on ultrasound guidance.

  20. Recent progress in lattice supersymmetry: from lattice gauge theory to black holes

    CERN Document Server

    Kadoh, Daisuke

    2016-01-01

    Supersymmetry (SUSY) is a fascinating topic in theoretical physics, because of its unique and counterintuitive properties. It is expected to emerge as new physics beyond the standard model, and it is also a building block for supergravity and superstring theory. A number of exact results obtained via SUSY theories provide insights into field theory. However, the dynamics of many SUSY theories are not yet fully understood, and numerical study of SUSY theories through lattice simulations is promising as regards furthering this understanding. In this paper, I overview the current status of lattice SUSY by discussing its development in chronological order, and by reviewing some simple models. In addition, I discuss the numerical verification of gauge/gravity duality, which is one of the recent significant developments in this field.

  1. Lattice topology dictates photon statistics.

    Science.gov (United States)

    Kondakci, H Esat; Abouraddy, Ayman F; Saleh, Bahaa E A

    2017-08-21

    Propagation of coherent light through a disordered network is accompanied by randomization and possible conversion into thermal light. Here, we show that network topology plays a decisive role in determining the statistics of the emerging field if the underlying lattice is endowed with chiral symmetry. In such lattices, eigenmode pairs come in skew-symmetric pairs with oppositely signed eigenvalues. By examining one-dimensional arrays of randomly coupled waveguides arranged on linear and ring topologies, we are led to a remarkable prediction: the field circularity and the photon statistics in ring lattices are dictated by its parity while the same quantities are insensitive to the parity of a linear lattice. For a ring lattice, adding or subtracting a single lattice site can switch the photon statistics from super-thermal to sub-thermal, or vice versa. This behavior is understood by examining the real and imaginary fields on a lattice exhibiting chiral symmetry, which form two strands that interleave along the lattice sites. These strands can be fully braided around an even-sited ring lattice thereby producing super-thermal photon statistics, while an odd-sited lattice is incommensurate with such an arrangement and the statistics become sub-thermal.

  2. Cyclic Oxidation of High Mo, Reduced Density Superalloys

    Directory of Open Access Journals (Sweden)

    James L. Smialek

    2015-11-01

    Full Text Available Cyclic oxidation was characterized as part of a statistically designed, 12-alloy compositional study of 2nd generation single crystal superalloys as part of a broader study to co-optimize density, creep strength, and cyclic oxidation. The primary modification was a replacement of 5 wt. % W by 7% or 12% Mo for density reductions of 2%–7%. Compositions at two levels of Mo, Cr, Co, and Re were produced, along with a midpoint composition. Initially, polycrystalline vacuum induction samples were screened in 1100 °C cyclic furnace tests using 1 h cycles for 200 h. The behavior was primarily delimited by Cr content, producing final weight changes of −40 mg/cm2 to −10 mg/cm2 for 0% Cr alloys and −2 mg/cm2 to +1 mg/cm2 for 5% Cr alloys. Accordingly, a multiple linear regression fit yielded an equation showing a strong positive Cr effect and lesser negative effects of Co and Mo. The results for 5% Cr alloys compare well to −1 mg/cm2, and +0.5 mg/cm2 for Rene′ N4 and Rene′ N5 (or Rene′ N6, respectively. Scale phases commonly identified were Al2O3, NiAl2O4, NiTa2O6, and NiO, with (Ni,CoMoO4 found only on the least resistant alloys having 0% Cr and 12% Mo. Scale microstructures were complex and reflected variations in the regional spallation history. Large faceted NiO grains and fine NiTa2O6 particles distributed along NiAl2O4 grain boundaries were typical distinctive features. NiMoO4 formation, decomposition, and volatility occurred for a few high Mo compositions. A creep, density, phase stability, and oxidation balanced 5% Cr, 10% Co, 7% Mo, and 3% Re alloy was selected to be taken forward for more extensive evaluations in single crystal form.

  3. Design of a biomimetic self-healing superalloy composite

    Science.gov (United States)

    Files, Bradley Steven

    1997-10-01

    Use of systems engineering concepts to design technologically advanced materials has allowed ambitious goals of self-healing alloys to be realized. Shape memory alloy reinforcements are embedded in an alloy matrix to demonstrate concepts of stable crack growth and matrix crack closure. Computer methods are used to design thermodynamically compatible iron-based alloys using bio-inspired concepts of crack bridging and self-healing. Feasibility of crack closure and stable crack growth is shown in a prototype system with a Sn-Bi matrix and TiNi fibers. Design of Fe-Ni-Co-Ti-Al alloys using thermodynamic models to determine stabilities and phase equilibria allows for a methodical system designing compatible multicomponent alloys for composite systems. Final alloy computations for this project led to the alloy Fe-27.6Ni-18.2Co-4.1Ti-1.6Al as a compatible shape memory a with a 650sp°C 90 minute heat treatment leading to martensite and austenite start temperatures (Msbs and Asbs) near room temperature. Thin slices of this alloy were able to fully recover at least 5% strain upon unloading heating. Composites made from the designed shape memory alloy and a compatible Fe-based B2 matrix were used to test self-healing concepts in the superalloy system. Diffusion couple experiments verified thermodynamic compatibility between matrix and reinforcement alloys at the solution treatment temperature of 1100sp°C. Concepts of stable crack growth and crack bridging were demonstrated in the composite, leading to enhanced toughness of the brittle matrix. However, healing behavior in this system was limited by intergranular fracture of the reinforcement alloy. It is believed that use of rapidly solidified powders could eliminate intergranular fracture, leading to greatly enhanced properties of toughening and healing. Crack clamping and stable crack growth were achieved in a feasibility study using a Sn-Bi matrix reinforced with TiNi fibers. Tensile specimens with less than 1% fibers

  4. Self-similar transformations of lattice-Ising models at critical temperatures

    CERN Document Server

    Feng, You-gang

    2012-01-01

    We classify geometric blocks that serve as spin carriers into simple blocks and compound blocks by their topologic connectivity, define their fractal dimensions and describe the relevant transformations. By the hierarchical property of transformations and a block-spin scaling law we obtain a relation between the block spin and its carrier's fractal dimension. By mapping we set up a block-spin Gaussian model and get a formula connecting the critical point and the minimal fractal dimension of the carrier, which guarantees the uniqueness of a fixed point corresponding to the critical point, changing the complicated calculation of critical point into the simple one of the minimal fractal dimension. The numerical results of critical points with high accuracy for five conventional lattice-Ising models prove our method very effective and may be suitable to all lattice-Ising models. The origin of fluctuations in structure at critical temperature is discussed. Our method not only explains the problems met in the renor...

  5. Ordered sets and lattices

    CERN Document Server

    Drashkovicheva, Kh; Igoshin, V I; Katrinyak, T; Kolibiar, M

    1989-01-01

    This book is another publication in the recent surveys of ordered sets and lattices. The papers, which might be characterized as "reviews of reviews," are based on articles reviewed in the Referativnyibreve Zhurnal: Matematika from 1978 to 1982. For the sake of completeness, the authors also attempted to integrate information from other relevant articles from that period. The bibliography of each paper provides references to the reviews in RZhMat and Mathematical Reviews where one can seek more detailed information. Specifically excluded from consideration in this volume were such topics as al

  6. Lattice Vibrations in Chlorobenzenes:

    DEFF Research Database (Denmark)

    Reynolds, P. A.; Kjems, Jørgen; White, J. W.

    1974-01-01

    Lattice vibrational dispersion curves for the ``intermolecular'' modes in the triclinic, one molecule per unit cell β phase of p‐C6D4Cl2 and p‐C6H4Cl2 have been obtained by inelastic neutron scattering. The deuterated sample was investigated at 295 and at 90°K and a linear extrapolation to 0°K...... by consideration of electrostatic forces or by further anisotropy in the dispersion forces not described in the atom‐atom model. Anharmonic effects are shown to be large, but the dominant features in the temperature variation of frequencies are describable by a quasiharmonic model....

  7. Lattice harmonics expansion revisited

    Science.gov (United States)

    Kontrym-Sznajd, G.; Holas, A.

    2017-04-01

    The main subject of the work is to provide the most effective way of determining the expansion of some quantities into orthogonal polynomials, when these quantities are known only along some limited number of sampling directions. By comparing the commonly used Houston method with the method based on the orthogonality relation, some relationships, which define the applicability and correctness of these methods, are demonstrated. They are verified for various sets of sampling directions applicable for expanding quantities having the full symmetry of the Brillouin zone of cubic and non-cubic lattices. All results clearly show that the Houston method is always better than the orthogonality-relation one. For the cubic symmetry we present a few sets of special directions (SDs) showing how their construction and, next, a proper application depend on the choice of various sets of lattice harmonics. SDs are important mainly for experimentalists who want to reconstruct anisotropic quantities from their measurements, performed at a limited number of sampling directions.

  8. Extreme lattices: symmetries and decorrelation

    Science.gov (United States)

    Andreanov, A.; Scardicchio, A.; Torquato, S.

    2016-11-01

    We study statistical and structural properties of extreme lattices, which are the local minima in the density landscape of lattice sphere packings in d-dimensional Euclidean space {{{R}}d} . Specifically, we ascertain statistics of the densities and kissing numbers as well as the numbers of distinct symmetries of the packings for dimensions 8 through 13 using the stochastic Voronoi algorithm. The extreme lattices in a fixed dimension of space d (d≥slant 8 ) are dominated by typical lattices that have similar packing properties, such as packing densities and kissing numbers, while the best and the worst packers are in the long tails of the distribution of the extreme lattices. We also study the validity of the recently proposed decorrelation principle, which has important implications for sphere packings in general. The degree to which extreme-lattice packings decorrelate as well as how decorrelation is related to the packing density and symmetry of the lattices as the space dimension increases is also investigated. We find that the extreme lattices decorrelate with increasing dimension, while the least symmetric lattices decorrelate faster.

  9. Elimination of spurious lattice fermion solutions and noncompact lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Lee, T.D.

    1997-09-22

    It is well known that the Dirac equation on a discrete hyper-cubic lattice in D dimension has 2{sup D} degenerate solutions. The usual method of removing these spurious solutions encounters difficulties with chiral symmetry when the lattice spacing l {ne} 0, as exemplified by the persistent problem of the pion mass. On the other hand, we recall that in any crystal in nature, all the electrons do move in a lattice and satisfy the Dirac equation; yet there is not a single physical result that has ever been entangled with a spurious fermion solution. Therefore it should not be difficult to eliminate these unphysical elements. On a discrete lattice, particle hop from point to point, whereas in a real crystal the lattice structure in embedded in a continuum and electrons move continuously from lattice cell to lattice cell. In a discrete system, the lattice functions are defined only on individual points (or links as in the case of gauge fields). However, in a crystal the electron state vector is represented by the Bloch wave functions which are continuous functions in {rvec {gamma}}, and herein lies one of the essential differences.

  10. On the construction of capacity-achieving lattice Gaussian codes

    KAUST Repository

    Alghamdi, Wael

    2016-08-15

    In this paper, we propose a new approach to proving results regarding channel coding schemes based on construction-A lattices for the Additive White Gaussian Noise (AWGN) channel that yields new characterizations of the code construction parameters, i.e., the primes and dimensions of the codes, as functions of the block-length. The approach we take introduces an averaging argument that explicitly involves the considered parameters. This averaging argument is applied to a generalized Loeliger ensemble [1] to provide a more practical proof of the existence of AWGN-good lattices, and to characterize suitable parameters for the lattice Gaussian coding scheme proposed by Ling and Belfiore [3]. © 2016 IEEE.

  11. Lattice Boltzmann Model for Compressible Fluid on a Square Lattice

    Institute of Scientific and Technical Information of China (English)

    SUN Cheng-Hai

    2000-01-01

    A two-level four-direction lattice Boltzmann model is formulated on a square lattice to simulate compressible flows with a high Mach number. The particle velocities are adaptive to the mean velocity and internal energy. Therefore, the mean flow can have a high Mach number. Due to the simple form of the equilibrium distribution, the 4th order velocity tensors are not involved in the calculations. Unlike the standard lattice Boltzmann model, o special treatment is need for the homogeneity of 4th order velocity tensors on square lattices. The Navier-Stokes equations were derived by the Chapman-Enskog method from the BGK Boltzmann equation. The model can be easily extended to three-dimensional cubic lattices. Two-dimensional shock-wave propagation was simulated

  12. Entangling gates in even Euclidean lattices such as Leech lattice

    CERN Document Server

    Planat, Michel

    2010-01-01

    We point out a organic relationship between real entangling n-qubit gates of quantum computation and the group of automorphisms of even Euclidean lattices of the corresponding dimension 2n. The type of entanglement that is found in the gates/generators of Aut() depends on the lattice. In particular, we investigate Zn lattices, Barnes-Wall lattices D4, E8, 16 (associated to n = 2, 3 and 4 qubits), and the Leech lattices h24 and 24 (associated to a 3-qubit/qutrit system). Balanced tripartite entanglement is found to be a basic feature of Aut(), a nding that bears out our recent work related to the Weyl group of E8 [1, 2].

  13. Thermophysical and structural study of IN 792-5A nickel based superalloy

    Directory of Open Access Journals (Sweden)

    S. Zlá

    2012-01-01

    Full Text Available The presented paper deals with study of phase transformations temperatures of nickel based superalloy IN 792-5A with application of DTA – method and use of experimental laboratory system for simultaneous thermal analysis SETARAM Setsys 18TM. Samples taken from as-received state of superalloy were heated with controlled ramp rates (1, 5, 10 and 20 °C•min-1 and immediately after melting they were cooled with the same controlled ramp rate. The samples before and after DTA-analysis were also subjected to the phase analysis with use of scanning electron microscopy on the microprobe (JCXA 733 equipped with energy dispersive analyser EDAX (EDAM 3.

  14. Rafting in single crystal nickel-base superalloys — An overview

    Indian Academy of Sciences (India)

    M Kamaraj

    2003-02-01

    Currently nickel-base single crystal (SX) superalloys are considered for the manufacture of critical components such as turbine blades, vanes etc., for aircraft engines as well as land-based power generation applications. Microstructure and high temperature mechanical properties are the major factors controlling the performance of SX superalloys. Rafting is an important phenomenon in these alloys which occurs during high temperature creep. It is essential to understand the rafting mechanism, and its characteristics on high temperature properties before considering the advanced applications. In this review article, the thermodynamic driving force for rafting with and without stress is explained. The nature and influence of rafting on creep properties including pre-rafted conditions are discussed. In addition, the effect of stress state on $\\gamma /\\gamma'$ rafting, kinetics and morphological evolution are discussed with the recent experimental results.

  15. QUANTITATIVE METALOGRAPHY OF HEAT TREATED ŽS6K SUPERALLOY

    Directory of Open Access Journals (Sweden)

    Juraj Belan

    2012-02-01

    Full Text Available Alloy ŽS6K is former USSR superalloy used in DV – 2 jet engine. It is used for turbine rotor blade and whole cast small sized rotors with working temperature up to 800 ÷ 1050°C. This alloy was evaluated after annealing at 800 °C/ 10 and followed by cooling with various rate, presented with cooling in water, oil and air. Cooling rates, represented by various cooling mediums, have a significant influence on diffusion processes, which are going in structure. Methods of quantitative metallography (Image Analyzer software NIS – Elements for carbides evaluation, measuring of secondary dendrite arm spacing and coherent testing grid for gama' - phase evaluation are used for evaluation of structural characteristics on experimental material – Ni base superalloy ŽS6K.

  16. QUANTITATIVE METALOGRAPHY OF HEAT TREATED ŽS6K SUPERALLOY

    Directory of Open Access Journals (Sweden)

    Juraj Belan

    2011-09-01

    Full Text Available Alloy ŽS6K is former USSR superalloy used in DV – 2 jet engine. It is used for turbine rotor blade and whole cast small sized rotors with working temperature up to 800 ÷ 1050°C. This alloy was evaluated after annealing at 800 °C/ 10 and followed by cooling with various rate, presented with cooling in water, oil and air. Cooling rates, represented by various cooling mediums, have a significant influence on diffusion processes, which are going in structure. Methods of quantitative metallography (Image Analyzer software NIS – Elements for carbides evaluation, measuring of secondary dendrite arm spacing and coherent testing grid for gama' - phase evaluation are used for evaluation of structural characteristics on experimental material – Ni base superalloy ŽS6K.

  17. Oxidation Resistance: One Barrier to Moving Beyond Ni-Base Superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Pint, Bruce A [ORNL; Distefano, James R [ORNL; Wright, Ian G [ORNL

    2006-01-01

    The implementation of new high-temperature materials is often hampered by their lack of oxidation or environmental resistance. This failing is one of the strongest barriers to moving beyond Ni-base superalloys for many commercial applications. In practice, usable high-temperature alloys have at least reasonable oxidation resistance, but the current generation of single-crystal Ni-base superalloys has sufficient oxidation resistance that optimized versions can be used without a metallic bond coating and only an oxygen-transparent ceramic coating for thermal protection. The material development process often centers around mechanical properties, while oxidation resistance, along with other realities, is given minor attention. For many applications, the assumption that an oxidation-resistant coating can be used to protect a substrate is seriously flawed, as coatings often do not provide sufficient reliability for critical components. Examples of oxidation problems are given for currently used materials and materials classes with critical oxidation resistance problems.

  18. Calorimetric examination of mixtures for modification of nickel and cobalt superalloys

    Directory of Open Access Journals (Sweden)

    F. Binczyk

    2009-04-01

    Full Text Available The study presents the results of thermodynamic calculations and calorimetric examination of thermal reactions taking place at hightemperatures between the nanoparticle inoculants and metallic constituents of nickel and cobalt superalloys. The calculations andmeasurements were made for different compositions, containing cobalt aluminate CoAl2O4, cobalt oxide CoO*Co2O3, zircon flourZrSi2O4, powdered and metallic Al, powdered Ti, and IN-713C alloy. The obtained results have indicated the possibility of using certainmixtures as potential inoculating additives for the volume modification of nickel and cobalt superalloys. A characteristic feature of these alloys is the formation of a detrimental structure containing very large columnar crystal, present even in castings of a very high solidification rate. It has been proved that the inoculant most effective in the formation of the structure of equiaxial grains is the inoculant based on cobalt aluminate, colloidal silica and powdered aluminium.

  19. STUDY OF THE MECHANICAL PROPERTIES OF INCONEL 718 SUPERALLOY AFTER HOT TENSILE TESTS

    Directory of Open Access Journals (Sweden)

    Tarcila Sugahara

    2014-10-01

    Full Text Available This research work investigated some important mechanical properties of Inconel 718 superalloy using hot tensile tests like conventional yield strength to 0.2% strain (σe , ultimate strength (σr , and specific elongation (εu . Samples were strained to failure at temperatures of 600°C, 650°C, 700°C, 750°C, 800°C and 850°C and strain rate of 0.5 mm/min (2 × 10–4 s–1 according to ASTM E-8. The results showed higher values σe of yield strength at 700°C, this anomalous behavior can be attributed to the presence of hardening precipitates as observed in the TTT diagram of superalloy Inconel 718. Examination of the sample’s surfaces tensile fracture showed that with increasing temperature test the actuating mechanism changes from intergranular fracture to coalescence of the microcavities.

  20. Processing and Microstructural Evolution of Superalloy Inconel 718 during Hot Tube Extrusion

    Institute of Scientific and Technical Information of China (English)

    Shihong ZHANG; Zhongtang WANG; Bing QIAO; Yi XU; Tingfeng XU

    2005-01-01

    The processing parameters of tube extrusion for superalloy Inconel 718 (IN 718), such as slug temperature, tools temperature, choice of lubricant, extrusion ratio and extrusion speed, were determined by experiment in this paper. An appropriate temperature range recommended for the slug is 1080~1120℃, and the temperature range recommended for the tools is 350~500℃. The microstructural evolution of superalloy IN 718 during tube extrusion was analyzed.With the increase of the deformation the cross crystal grains were slightly refined. While the vertical crystal grain is elongated evidently and the tensile strength increased along the axial rake. Glass lubricants have to be spread on the slug surface after being heated to 150~200℃, vegetable oil or animal oil can be used as the lubricant on the surface of the tools to reduce the extrusion force remarkably.

  1. Cyclic Oxidation and Hot Corrosion of NiCrY-Coated Disk Superalloys

    Science.gov (United States)

    Gabb, Timothy P.; Miller, Robert A.; Sudbrack, Chantal K.; Draper, Susan L.; Nesbitt, James A.; Rogers, Richard B.; Telesman, Ignacy; Ngo, Vanda; Healy, Jonathan

    2016-01-01

    Powder metallurgy disk superalloys have been designed for higher engine operating temperatures through improvement of their strength and creep resistance. Yet, increasing disk application temperatures to 704 degrees Centigrade and higher could enhance oxidation and activate hot corrosion in harmful environments. Protective coatings could be necessary to mitigate such attack. Cylindrical coated specimens of disk superalloys LSHR and ME3 were subjected to thermal cycling to produce cyclic oxidation in air at a maximum temperature of 760 degrees Centigrade. The effects of substrate roughness and coating thickness on coating integrity after cyclic oxidation were considered. Selected coated samples that had cyclic oxidation were then subjected to accelerated hot corrosion tests. This cyclic oxidation did not impair the coating's resistance to subsequent hot corrosion pitting attack.

  2. XPS surface analysis of chemical and ion nitred Ni-base superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Cappelli, E.; Nistico' , N.; Giunta, G.; Musicanti, M.; Bovaro, A.; Visconti, A. (Eniricerche, Monterotondo (Italy) Soliveri SpA, Caravaggio (Italy) Vacuum SpA, Trezzano S.N. (Italy))

    This paper reports on an investigation of the possibility of inducing surface modifications in a nickel base superalloy through different nitride treatment methods analogous to conventional hardening processes for steels. The aim was to confer, to the external surface of the superalloy, chemical and mechanical characteristics such as to make possible the nucleation and growth of a follow-up layer of a ceramic material (chemical vapour deposited TiN). The idea was to obtain good materials adhesion characterized by optimum properties - elastic modulus, thermal expansion, crystal structure, morphology, etc. The treatments led to significant increases in surface hardness and positively influenced both the nucleation process and TiN growth, as well as, substrate and coating adhesion. Results of x-ray photoelectron spectroscopy, XPS, of the surface and internal layers, together with microstructural examinations (SEM- EDX, XRD), evidenced the presence of nitrogen and the formation of nitrides (CrN and TiN) responsible for the induced modifications.

  3. Retention of Compressive Residual Stresses Introduced by Shot Peening in a Powder Metal Disk Superalloy

    Science.gov (United States)

    Gabb, Timothy P.; Danetti, Andrew; Draper, Susan L.; Locci, Ivan E.; Telesman, Jack

    2016-01-01

    The fatigue lives of disk superalloys can be increased by shot peening their surfaces, to induce compressive residual stresses near the surface that impede cracking there. As disk application temperatures increase for improved efficiency, the persistence of these beneficial stresses could be impaired, especially with continued fatigue cycling. The objective of this work was to study the retention of residual stresses introduced by shot peening, when subjected to fatigue and high temperatures. Fatigue specimens of powder metallurgy processed nickel-base disk superalloy ME3 were prepared with consistent processing and heat treatment. They were then shot peened using varied conditions. Strain-controlled fatigue cycles were run at room temperature and 704 C, to allow re-assessment of residual stresses.

  4. Fabrication of directional solidification components of nickel-base superalloys by laser metal forming

    Institute of Scientific and Technical Information of China (English)

    Liping Feng; Weidong Huang; Darong Chen; Xin Lin; Haiou Yang

    2004-01-01

    Straight plates, hollow columns, ear-like blade tips, twist plates with directional solidification microstructure made of Rene 95 superalloys were successfully fabricated on Nickel-base superalloy and DD3 substrates, respectively. The processing conditions for production of the parts with corresponding shapes were obtained. The fabrication precision was high and the components were compact. The solidification microstructure of the parts was analyzed by optical microscopy. The results show that the solidification microstructure is composed of columnar dendrites, by epitaxial growth onto the directional solidification substrates. The crystallography orientation of the parts was parallel to that of the substrates. The primary arm spacing was about 10 μm, which is in the range of superfine dendrites, and the secondary arm was small or even degenerated. It is concluded that the laser metal forming technique provides a method to manufacture directional solidification components.

  5. Microstructure of the Nickel-Base Superalloy CMSX-4 Fabricated by Selective Electron Beam Melting

    Science.gov (United States)

    Ramsperger, Markus; Singer, Robert F.; Körner, Carolin

    2016-03-01

    Powder bed-based additive manufacturing (AM) processes are characterized by very high-temperature gradients and solidification rates. These conditions lead to microstructures orders of magnitude smaller than in conventional casting processes. Especially in the field of high performance alloys, like nickel-base superalloys, this opens new opportunities for homogenization and alloy development. Nevertheless, the high susceptibility to cracking of precipitation-hardenable superalloys is a challenge for AM. In this study, electron beam-based AM is used to fabricate samples from gas-atomized pre-alloyed CMSX-4 powder. The influence of the processing strategy on crack formation is investigated. The samples are characterized by optical and SEM microscopy and analyzed by microprobe analysis. Differential scanning calorimetry is used to demonstrate the effect of the fine microstructure on characteristic temperatures. In addition, in situ heat treatment effects are investigated.

  6. Optimizing the heat treatment of Ni-based superalloy turbine discs

    Science.gov (United States)

    Furrer, D. U.; Shankar, R.; White, C.

    2003-03-01

    The heat-treatment processes for nickel-based superalloys continue to change due to the development of new alloys, new requirements, and subsequent new manufacturing facilities. Nickel-based superalloys are continuing to evolve to meet emerging applications, while new alloys are also being introduced for advanced applications. These new materials are also being optimized for numerous mechanical and physical properties, making the selection of heat-treatment parameters increasingly challenging. New processing facilities and methods are also being implemented to allow tailoring of heat-treating parameters to meet these new challenges. For example, the Ladish SuperCooler technology allows engineering and control of all aspects of the heat-treatment process for nickel-based components, resulting in never-before possible disc properties.

  7. High Temperature Spin Testing of a Superalloy Disk With a Dual Grain Structure

    Science.gov (United States)

    Gayda, John; Kantzos, Pete

    2002-01-01

    Comparative spin tests were run on superalloy disks at an elevated temperature to determine the benefits of a DMHT disk, with a fine grain bore and coarse grain rim, versus a traditional subsolvus disk with a fine grain structure in the bore and rim. The results of these tests showed that the DMHT disk exhibited significantly lower growth at 1500 F. Further, the results of these tests could be accurately predicted using a 2D viscoelastic finite element analysis. These results indicate DMHT technology can be used to extend disk operating temperatures when compared to traditional subsolvus heat treatment options for superalloy disks. However, additional research is required to ensure the safe operation of a DMHT disk under more realistic engine operating conditions. This includes testing to determine the burst margin and cyclic capability of DMHT disks in a spin pit, at a minimum, and ultimately running an engine test with a DMHT disk.

  8. Development of superalloys for 1700 C ultra-efficient gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Harada, Hiroshi [National Institute for Materials Science, Tsukuba, Ibaraki (Japan). High Temperature Materials Center

    2010-07-01

    Mitigation of global warming is one of the most outstanding issues for the humankind. The Japanese government announced that it will reduce its greenhouse gas emissions by 25% from the 1990 level by 2020 as a medium-term goal. One of the promising approaches to achieving this is to improve the efficiency of thermal power plants emitting one-third of total CO{sub 2} gas in Japan. The key to improving the thermal efficiency is high temperature materials with excellent temperature capabilities allowing higher inlet gas temperatures. In this context, new single crystal superalloys for turbine blades and vanes, new coatings and turbine disk superalloys have been successfully developed for various gas turbine applications, typically 1700 C ultra-efficient gas turbines for next generation combine cycle power plants. (orig.)

  9. DENDRITE REFINING AND EUTECTIC TRANSFORMATION BEHAVIOR OF NICKEL-BASE SINGLE CRYSTAL (NBSC) SUPERALLOY

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    Because of the low temperature gradient and growth rate, the microstructure of the conventional single crystal superalloy made by HRS processing is coarse dendrite with well developed sidebranches and has serious segregation. With the help of the high temperature gradient directional solidification equipment (HGDS), the solidification cooling rate is greatly increased. Study on microstructure of the Ni-base single crystal superalloy solidified at much higher cooling rate shows that the dendrite arm spacing is highly refined, of which the primary dendrite arm spacing can be made to be 38μm, just as 1/10 as that by conventional HRS processing. With the increase of the cooling rate, the amount of the eutectic increases and then decreases. In the superfine columnar dendrite, the amount of γ/γ′eutectic is much fewer and its size is very small. This is useful to homogenize the microsegregation and improve the property of the material.

  10. Cyclic Oxidation and Hot Corrosion of NiCrY-Coated Disk Superalloy

    Science.gov (United States)

    Gabb, Tim; Miller, R. A.; Sudbrack, C. K.; Draper, S. L.; Nesbitt, J.; Telesman, J.; Ngo, V.; Healy, J.

    2015-01-01

    Powder metallurgy disk superalloys have been designed for higher engine operating temperatures through improvement of their strength and creep resistance. Yet, increasing disk application temperatures to 704 C and higher could enhance oxidation and activate hot corrosion in harmful environments. Protective coatings could be necessary to mitigate such attack. Cylindrical coated specimens of disk superalloys LSHR and ME3 were subjected to thermal cycling to produce cyclic oxidation in air at a maximum temperature of 760 C. The effects of substrate roughness and coating thickness on coating integrity after cyclic oxidation were considered. Selected coated samples that had cyclic oxidation were then subjected to accelerated hot corrosion tests. The effects of this cyclic oxidation on resistance to subsequent hot corrosion attack were examined.

  11. A study of microstructural characteristics and differential thermal analysis of Ni-based superalloys

    Science.gov (United States)

    Aggarwal, M. D.; Lal, R. B.; Oyekenu, Samuel A.; Parr, Richard; Gentz, Stephen

    1989-01-01

    The objective of this work is to correlate the mechanical properties of the Ni-based superalloy MAR M246(Hf) used in the Space Shuttle Main Engine with its structural characteristics by systematic study of optical photomicrographs and differential thermal analysis. The authors developed a method of predicting the liquidus and solidus temperature of various nickel based superalloys (MAR-M247, Waspaloy, Udimet-41, polycrystalline and single crystals of CMSX-2 and CMSX-3) and comparing the predictions with the experimental differential thermal analysis (DTA) curves using Perkin-Elmer DTA 1700. The method of predicting these temperatures is based on the additive effect of the components dissolved in nickel. The results were compared with the experimental values.

  12. Susceptibility to Hot Cracking and Weldment Heat Treatment of Haynes 230 Superalloy

    Institute of Scientific and Technical Information of China (English)

    C.M.Cheng; C.P.Chou; I.K.Lee; I.C.Kuo

    2006-01-01

    This study investigates the susceptibility of hot cracking and weldment heat treatment of Haynes 230 superalloy.The Varestriant test was conducted to evaluate this susceptibility. Welding was performed by gas tungsten arc welding(GTAW)and plasma arc welding(PAW)with stress relief heat treatment and solid solution heat treatment. A tensile test is then performed to measure the changes in the mechanical properties of the heattreated material. The results indicate that the number of thermal cycles does not affect the susceptibility of Haynes 230 superalloy to hot cracking. However, it does increase the strain. In weldment of heat treatment,stress relief annealing increases the yield strength and tensile strength of the welded parts. The section of the tensile specimens shows fibrous fractures on the welded parts, regardless of whether they are heat-treated.

  13. Effect of Grinding Temperatures on the Surface Integrity of a Nickel-based Superalloy

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    An experimental study was carried out to investigat e the influence of temperatures on workpiece surface integrity in surface grinding of a cast nickel-based superalloy with alumina abrasive wheels. Temperatur e response at the wheel-workpiece interface was measured using a grindable foil /workpiece thermocouple. Specimens with different grinding temperatures were obt ained through changing grinding conditions including depth of cut, workpiece fee d speed, and coolant supply. Changes in surface roughnes...

  14. Calorimetric examination of mixtures for modification of nickel and cobalt superalloys

    OpenAIRE

    F. Binczyk; J. Sleziona; R. Przeliorz

    2009-01-01

    The study presents the results of thermodynamic calculations and calorimetric examination of thermal reactions taking place at hightemperatures between the nanoparticle inoculants and metallic constituents of nickel and cobalt superalloys. The calculations andmeasurements were made for different compositions, containing cobalt aluminate CoAl2O4, cobalt oxide CoO*Co2O3, zircon flourZrSi2O4, powdered and metallic Al, powdered Ti, and IN-713C alloy. The obtained results have indicated the possib...

  15. Stem-EDX and FIB-SEM Tomography of ALLVAC 718Plus Superalloy

    Directory of Open Access Journals (Sweden)

    Kruk A.

    2016-06-01

    Full Text Available Allvac 718Plus (718Plus is a high strength, corrosion resistant nickel- based superalloy used for application in power generation, aeronautics and aerospace industry. The 718Plus microstructure consists of a γ matrix with γ’-Ni3(Al,Ti and some δ- Ni3Nb phases as well as lamellar particles (η-Ni3Ti, η*-Ni6AlNb or Ni6(Al,TiNb precipitated at the grain boundaries.

  16. Computational and Experimental Design of Fe-Based Superalloys for Elevated-Temperature Applications

    Energy Technology Data Exchange (ETDEWEB)

    Liaw, Peter K. [Univ. of Tennessee, Knoxville, TN (United States); Fine, Morris E. [Northwestern Univ., Evanston, IL (United States); Ghosh, Gautam [Northwestern Univ., Evanston, IL (United States); Asta, Mark D. [Univ. of California, Berkeley, CA (United States); Liu, Chain T. [Auburn Univ., AL (United States); Sun, Zhiqian [Univ. of Tennessee, Knoxville, TN (United States); Huang, Shenyan [Univ. of Tennessee, Knoxville, TN (United States); Teng, Zhenke [Univ. of Tennessee, Knoxville, TN (United States); Wang, Gongyao [Univ. of Tennessee, Knoxville, TN (United States)

    2012-04-13

    Analogous to nickel-based superalloys, Fe-based superalloys, which are strengthened by coherent B2- type precipitates are proposed for elevated-temperature applications. During the period of this project, a series of ferritic superalloys have been designed and fabricated by methods of vacuum-arc melting and vacuum-induction melting. Nano-scale precipitates were characterized by atom-probe tomography, ultrasmall- angle X-ray scattering, and transmission-electron microscopy. A duplex distribution of precipitates was found. It seems that ferritic superalloys are susceptible to brittle fracture. Systematic endeavors have been devoted to understanding and resolving the problem. Factors, such as hot rolling, precipitate volume fractions, alloy compositions, precipitate sizes and inter-particle spacings, and hyperfine cooling precipitates, have been investigated. In order to understand the underlying relationship between the microstructure and creep behavior of ferric alloys at elevated temperatures, in-situ neutron studies have been carried out. Based on the current result, it seems that the major role of β' with a 16%-volume fraction in strengthening ferritic alloys is not load sharing but interactions with dislocations. The oxidation behavior of one ferritic alloy, FBB8 (Fe-6.5Al-10Ni-10Cr-3.4Mo-0.25Zr-0.005B, weight percent), was studied in dry air. It is found that it possesses superior oxidation resistance at 1,023 and 1,123 K, compared with other creep-resistant ferritic steels [T91 (modified 9Cr-1Mo, weight percent) and P92 (9Cr-1.8W-0.5Mo, weight percent)]. At the same time, the calculation of the interfacial energies between the -iron and B2-type intermetallics (CoAl, FeAl, and NiAl) has been conducted.

  17. HIGH-TEMPERATURE LOW CYCLE FATIGUE BEHAVIOR OFNICKEL BASE SUPERALLOY GH536

    Institute of Scientific and Technical Information of China (English)

    M. Zhao; L.Y. Xu; K.S. Zhang; B.Y. Yang

    2001-01-01

    Low cycle fatigue tests on nickel base superalloy GH536 were performed at 600. 700and 800°C. The strain-life and cyclic stress-strain relationship were given at various temperatures. The change in fatigue life behavior and fatigue parameters with temperature increasing was discussed. At low and intermediate total strain amplitudes,the fatigue life was found to decrease with increasing temperature.``

  18. Interdiffusion between Ni-based superalloy and MCrAlY coating

    DEFF Research Database (Denmark)

    Dahl, Kristian Vinter; Hald, John; Horsewell, Andy

    2006-01-01

    Interdiffusion at the interface between a Co-36.5Ni-17.5Cr-8Al-0.5Y, MCrAlY coating and the underlying IN738 superalloy was studied in a large matrix of specimens isothermally heat treated for up to 12,000 hours at temperatures 875oC, 925oC or 950oC. Modelled results using the finite difference...

  19. Solution heat-treatment of Nb-modified MAR-M247 superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Soares Azevedo e Silva, Paulo Ricardo, E-mail: paulori@alunos.eel.usp.br [Universidade de Sao Paulo (USP), Escola de Engenharia de Lorena (EEL), Departamento de Engenharia de Materiais DEMAR, Polo Urbo-Industrial Gleba AI-6, Caixa Postal 116, 12600-970, Lorena, Sao Paulo (Brazil); Baldan, Renato, E-mail: renato@ppgem.eel.usp.br [Universidade de Sao Paulo (USP), Escola de Engenharia de Lorena (EEL), Departamento de Engenharia de Materiais DEMAR, Polo Urbo-Industrial Gleba AI-6, Caixa Postal 116, 12600-970, Lorena, Sao Paulo (Brazil); Nunes, Carlos Angelo, E-mail: cnunes@demar.eel.usp.br [Universidade de Sao Paulo (USP), Escola de Engenharia de Lorena (EEL), Departamento de Engenharia de Materiais DEMAR, Polo Urbo-Industrial Gleba AI-6, Caixa Postal 116, 12600-970, Lorena, Sao Paulo (Brazil); Carvalho Coelho, Gilberto, E-mail: coelho@demar.eel.usp.br [Universidade de Sao Paulo (USP), Escola de Engenharia de Lorena (EEL), Departamento de Engenharia de Materiais DEMAR, Polo Urbo-Industrial Gleba AI-6, Caixa Postal 116, 12600-970, Lorena, Sao Paulo (Brazil); UniFoa, Centro Universitario de Volta Redonda, Nucleo de Pesquisa, Campus Tres Pocos, Avenida Paulo Erlei Alves Abrantes, 1325, Bairro Tres Pocos, 27240-560, Volta Redonda, Rio de Janeiro (Brazil); and others

    2013-01-15

    MAR-M247 superalloy has excellent mechanical properties and good oxidation resistance at elevated temperatures. Niobium is an element known as {gamma} Prime phase hardener in nickel-based superalloys, besides promoting homogeneous distribution of MC carbides. This work is inserted in a project that aims to evaluate the total replacement of tantalum by niobium atoms in MAR-M247 superalloy (10.2 Co, 10.2 W, 8.5Cr, 5.6 Al, 1.6 Nb, 1.4 Hf, 1.1 Ti, 0.7 Mo, 0.15 C, 0.06 Zr, 0.015 B, Ni balance-wt.%). Based on microstructural characterizations (SEM and FEG-SEM, both with EDS) of the as-cast material and heat-treated materials as well as utilizing Thermocalc simulations and experiments of differential thermal analysis (DTA), heat-treatment at 1260 Degree-Sign C for 8 h was chosen as an ideal condition for the solution of Nb-modified MAR-M247 superalloy. The hardness of as-cast and ideally solution treated materials was 390 {+-} 14 HV and 415 {+-} 6 HV, respectively. - Highlights: Black-Right-Pointing-Pointer DTA and microstructure of MAR-M247(Nb) showed a good agreement with Thermocalc. Black-Right-Pointing-Pointer An ideal condition for solution heat-treatment of MAR-M247(Nb) is 1260 Degree-Sign C for 8 h. Black-Right-Pointing-Pointer It was an observed evidence of incipient melting in samples heat-treated at 1280 Degree-Sign C.

  20. Misorientation related microstructure at the grain boundary in a nickel-based single crystal superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Ming; Zhuo, Longchao [National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, The State Key Laboratory of New Ceramics and Fine Processing, Laboratory of Advanced Materials (MOE), Tsinghua University, Beijing 100084 (China); Liu, Zhanli [Applied Mechanics Lab, School of Aerospace, Tsinghua University, Beijing 100084 (China); Lu, Xiaogang [School of Materials Science and Engineering, Shanghai University, Shanghai (China); Shi, Zhenxue; Li, Jiarong [Science and Technology on Advanced High Temperature Structural Materials Laboratory, Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Zhu, Jing, E-mail: jzhu@mail.tsinghua.edu.cn [National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, The State Key Laboratory of New Ceramics and Fine Processing, Laboratory of Advanced Materials (MOE), Tsinghua University, Beijing 100084 (China)

    2015-07-29

    The mechanical properties of nickel-based single crystal superalloys deteriorate with increasing misorientation, thus the finished product rate of the casting of single crystal turbine airfoils may be reduced due to the formation of grain boundaries especially when the misorientation angle exceeds to some extent. To this day, evolution of the microstructures at the grain boundaries with misorientation and the relationship between the microstructures and the mechanical properties are still unclear. In this work a detailed characterization of the misorientation related microstructure at the grain boundary in DD6 single crystal superalloy has been carried out using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques; the elemental distribution at the grain boundaries has been analyzed by energy dispersive (EDS) X-ray mapping; and the effect of precipitation of μ phases at the grain boundary on the mechanical property has been evaluated by finite element calculation. It is shown that the proportion of γ phase at the grain boundaries decreases, while the proportion of γ′ phase at the grain boundaries increases with increasing misorientation; the μ phase is precipitated at the grain boundaries when the misorientation angle exceeds about 10° and thus it could lead to a dramatic deterioration of the mechanical properties, as well as that the enrichment of Re and W gradually disappears as the misorientation angle increases. All these factors may result in the degradation of the mechanical properties at the grain boundaries as the misorientation increases. Furthermore, the finite element calculation confirms that precipitation of μ phases at the grain boundary is responsible for the significant deterioration of the mechanical properties when the misorientation exceeds about 10°. This work provides a physical imaging of the microstructure for understanding the relationship between the mechanical properties and the misorientation

  1. Interdiffusion between Ni-based superalloy and MCrAlY coating

    DEFF Research Database (Denmark)

    Dahl, Kristian Vinter; Hald, John; Horsewell, Andy

    2006-01-01

    Interdiffusion at the interface between a Co-36.5Ni-17.5Cr-8Al-0.5Y, MCrAlY coating and the underlying IN738 superalloy was studied in a large matrix of specimens isothermally heat treated for up to 12,000 hours at temperatures 875oC, 925oC or 950oC. Modelled results using the finite difference...

  2. Development of advanced P/M Ni-base superalloys for turbine disks

    OpenAIRE

    Garibov Genrikh S.; Grits Nina M.; Vostrikov Alexey V.; Fedorenko Yelizaveta A.; Volkov Alexander M.

    2014-01-01

    In the process of evolution of powder metallurgy in Russia the task permanently formulated was the following: to improve strength properties of P/M superalloys without application of additional complex HIPed blanks deformation operation. On the other hand development of a turbine disk material structure to ensure an improvement in aircraft engine performance requires the use of special HIP and heat treatment conditions. To ensure maximum strength properties of disk materials it is necessary t...

  3. Microstructurally sensitive crack nucleation around inclusions in powder metallurgy nickel based superalloys

    OpenAIRE

    Jiang, J; Yang, J; Zhang, T.; J Zou; Wang,Y.,; Dunne, F.P.E.; Britton, T. B.

    2016-01-01

    ? 2016 Acta Materialia Inc.Nickel-based superalloys are used in high strength, high-value applications, such as gas turbine discs in aero engines. In these applications the integrity of the disc is critical and therefore understanding crack initiation mechanisms is of high importance. With an increasing trend towards powder metallurgy routes for discs, sometimes unwanted non-metallic inclusions are introduced during manufacture. These inclusions vary in size from ?10??m to 200??m which is com...

  4. Factors affecting the corrosion fatigue life in nickel based superalloys for disc applications

    OpenAIRE

    Rosier Hollie; Perkins Karen; Girling Andrew; Leggett Jonathan; Gibson Grant

    2014-01-01

    The nickel based superalloy 720Li is employed in the gas turbine due to its mechanical performance at elevated temperature. A comprehensive assessment of the materials behaviour under representative service conditions is reported to address the drive for ever increasing temperatures and more arduous environmental exposure. Fatigue experiments have been performed in an air and air/SOx environment at 700 ∘C containing a mixed salt as a contaminant. There is an intimate relationship between loca...

  5. Use of Precious Metal-Modifed Nickel-Base Superalloys for Thin Gage Applications (Preprint)

    Science.gov (United States)

    2011-04-01

    Historically, sandwich construction MTPS (outer surface-Alloy 617 nickel-base superalloy honeycomb core and face sheets; inner surface titanium alloy honeycomb ...National Aeronautics and Space Administration ( NASA ) X-33 vehicle2, a wedged-shaped subscale prototype of a reusable launch vehicle4 designed by...MTPS, materials under consideration must be very thin, 0.17 mm-0.25 mm for a typical face sheet and 0.05mm-0.10 mm for honeycomb core. One

  6. Development of the recovery technology for nickel superalloy blades of the aircraft engine by laser cladding

    Science.gov (United States)

    Bykovskiy, D. P.; Petrovskiy, V. N.; Polskiy, V. I.; Chirikov, S. N.; Dzhumaev, P. S.

    2016-09-01

    Development of cladding modes was performed with a superalloy nickel based powder on a flat substrate from material identical to compressor and turbine blades. Cross sections were made, and a visual inspection of the shape and the quality of the clad track as well as themetallographic analysis were performed. Microhardness of the deposition zone, chemical composition of the base, cladded metals, and the heat affected zone were determined.

  7. Crystallographic, microstructure and mechanical characteristics of dynamically processed IN718 superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, A.D., E-mail: ads.hpu@gmail.com [Department of Physics, Himachal Pradesh University, Shimla 171005 (India); Sharma, A.K. [Terminal Ballistics Research Laboratory, Chandigarh 160030 (India); Thakur, N. [Department of Physics, Himachal Pradesh University, Shimla 171005 (India)

    2014-06-01

    Highlights: • Measurement of detonation velocity and compaction of powder are achieved together. • A plastic explosive detonation results into dense compacts without grain-growth. • We have studied crystallographic, micromechanical and microstructural features. • The results show no segregation within the compacts. • Density (98%), microhardness (470 ± 3)H{sub v}, microstrain (0.3%), UTS (806 MPa) are obtained. - Abstract: Dynamic consolidation of IN718 superalloy powder without grain-growth and negligible density gradient is accomplished through explosively generated shock wave loading. The compaction of powder and measurement of detonation velocity are achieved successfully in a single-shot experiment by employing instrumented detonics. A plastic explosive having a detonation velocity of the order of 7.1 km/s in a direct proximity with superalloy powder is used for the consolidation process. The compacted specimens are examined for structural, microstructure and mechanical characteristics. X-ray diffraction (XRD) study suggests intact crystalline structure of the compacts. A small micro-strain (0.26%) is observed by using Williamson–Hall method. Wavelength dispersive spectroscopy indicates no segregation within the shock processed superalloy compacted specimens. The monoliths investigated for fractography by using field emission scanning electron microscopy (FE-SEM) show original dendritic structure accompanied by re-solidified molten regions across the interparticle boundaries. Depth-sensing indentations (at 1.96 N) on compacted specimens show excellent micro-hardness of the order of (470 ± 3)H{sub v}. Tensile and compressive strengths of the superalloy monolith are observed to be 806 and 822 MPa, respectively.

  8. Predicting the onset of rafting of c 0 precipitates by channel deformation in a Ni superalloy

    OpenAIRE

    Ratel-Ramond, Nicolas; Calderon, H. A.; MORI, T.; Withers, Philip J.

    2010-01-01

    Abstract The growth or shrinkage, normal to {001}, of the interfaces between the ? matrix and cuboidal ?' precipitates is examined for a Ni-base superalloy, by considering the force acting on the interfaces. The force is produced by the precipitate coherency misfit and the stress produced by plastic deformation in channels of the ? matrix. A simple expression, which directly addresses the origin of the surface force, is given. The plastic deformation within the initially activ...

  9. Long-range interactions in lattice field theory

    Energy Technology Data Exchange (ETDEWEB)

    Rabin, J.M.

    1981-06-01

    Lattice quantum field theories containing fermions can be formulated in a chirally invariant way provided long-range interactions are introduced. It is established that in weak-coupling perturbation theory such a lattice theory is renormalizable when the corresponding continuum theory is, and that the continuum theory is indeed recovered in the perturbative continuum limit. In the strong-coupling limit of these theories one is led to study an effective Hamiltonian describing a Heisenberg antiferromagnet with long-range interactions. Block-spin renormalization group methods are used to find a critical rate of falloff of the interactions, approximately as inverse distance squared, which separates a nearest-neighbor-antiferromagnetic phase from a phase displaying identifiable long-range effects. A duality-type symmetry is present in some block-spin calculations.

  10. Introduction to lattice gauge theory

    Science.gov (United States)

    Gupta, R.

    The lattice formulation of Quantum Field Theory (QFT) can be exploited in many ways. We can derive the lattice Feynman rules and carry out weak coupling perturbation expansions. The lattice then serves as a manifestly gauge invariant regularization scheme, albeit one that is more complicated than standard continuum schemes. Strong coupling expansions: these give us useful qualitative information, but unfortunately no hard numbers. The lattice theory is amenable to numerical simulations by which one calculates the long distance properties of a strongly interacting theory from first principles. The observables are measured as a function of the bare coupling g and a gauge invariant cut-off approx. = 1/alpha, where alpha is the lattice spacing. The continuum (physical) behavior is recovered in the limit alpha yields 0, at which point the lattice artifacts go to zero. This is the more powerful use of lattice formulation, so in these lectures the author focuses on setting up the theory for the purpose of numerical simulations to get hard numbers. The numerical techniques used in Lattice Gauge Theories have their roots in statistical mechanics, so it is important to develop an intuition for the interconnection between quantum mechanics and statistical mechanics.

  11. Dark matter on the lattice

    OpenAIRE

    Lewis, Randy

    2014-01-01

    Several collaborations have recently performed lattice calculations aimed specifically at dark matter, including work with SU(2), SU(3), SU(4) and SO(4) gauge theories to represent the dark sector. Highlights of these studies are presented here, after a reminder of how lattice calculations in QCD itself are helping with the hunt for dark matter.

  12. Fast simulation of lattice systems

    DEFF Research Database (Denmark)

    Bohr, H.; Kaznelson, E.; Hansen, Frank;

    1983-01-01

    A new computer system with an entirely new processor design is described and demonstrated on a very small trial lattice. The new computer simulates systems of differential equations of the order of 104 times faster than present day computers and we describe how the machine can be applied to lattice...

  13. Branes and integrable lattice models

    CERN Document Server

    Yagi, Junya

    2016-01-01

    This is a brief review of my work on the correspondence between four-dimensional $\\mathcal{N} = 1$ supersymmetric field theories realized by brane tilings and two-dimensional integrable lattice models. I explain how to construct integrable lattice models from extended operators in partially topological quantum field theories, and elucidate the correspondence as an application of this construction.

  14. Charmed baryons on the lattice

    CERN Document Server

    Padmanath, M

    2015-01-01

    We discuss the significance of charm baryon spectroscopy in hadron physics and review the recent developments of the spectra of charmed baryons in lattice calculations. Special emphasis is given on the recent studies of highly excited charm baryon states. Recent precision lattice measurements of the low lying charm and bottom baryons are also reviewed.

  15. Quantum phases in optical lattices

    NARCIS (Netherlands)

    Dickerscheid, Dennis Brian Martin

    2006-01-01

    An important new development in the field of ultracold atomic gases is the study of the properties of these gases in a so-called optical lattice. An optical lattice is a periodic trapping potential for the atoms that is formed by the interference pattern of a few laser beams. A reason for the

  16. Feasibility of Electrochemical Deposition of Nickel/Silicon Carbide Fibers Composites over Nickel Superalloys

    Science.gov (United States)

    Ambrosio, E. P.; Abdul Karim, M. R.; Pavese, M.; Biamino, S.; Badini, C.; Fino, P.

    2017-02-01

    Nickel superalloys are typical materials used for the hot parts of engines in aircraft and space vehicles. They are very important in this field as they offer high-temperature mechanical strength together with a good resistance to oxidation and corrosion. Due to high-temperature buckling phenomena, reinforcement of the nickel superalloy might be needed to increase stiffness. For this reason, it was thought to investigate the possibility of producing composite materials that might improve properties of the metal at high temperature. The composite material was produced by using electrochemical deposition method in which a composite with nickel matrix and long silicon carbide fibers was deposited over the nickel superalloy. The substrate was Inconel 718, and monofilament continuous silicon carbide fibers were chosen as reinforcement. Chemical compatibility was studied between Inconel 718 and the reinforcing fibers, with fibers both in an uncoated condition, and coated with carbon or carbon/titanium diboride. Both theoretical calculations and experiments were conducted, which suggested the use of a carbon coating over the fibers and a buffer layer of nickel to avoid unwanted reactions between the substrate and silicon carbide. Deposition was then performed, and this demonstrated the practical feasibility of the process. Yield strength was measured to detect the onset of interface debonding between the substrate and the composite layer.

  17. Study of Flow Softening Mechanisms of a Nickel-Based Superalloy With Δ Phase

    Directory of Open Access Journals (Sweden)

    Lin Y.C.

    2016-09-01

    Full Text Available The flow softening behaviors of a nickel-based superalloy with δ phase are investigated by hot compression tests over wide ranges of deformation temperature and strain rate. Electron backscattered diffraction (EBSD, optical microscopy (OM, and scanning electron microscopy (SEM are employed to study the flow softening mechanisms of the studied superalloy. It is found that the flow softening behaviors of the studied superalloy are sensitive to deformation temperature and strain rate. At high strain rate and low deformation temperature, the obvious flow softening behaviors occur. With the increase of deformation temperature or decrease of strain rate, the flow softening degree becomes weaken. At high strain rate (1s−1, the flow softening is mostly induced by the plastic deformation heating and flow localization. However, at low strain rate domains (0.001-0.01s−1, the effects of deformation heating on flow softening are slight. Moreover, the flow softening at low strain rates is mainly induced by the discontinuous dynamic recrystallization and the dissolution of δ phase (Ni3Nb.

  18. Computational and experimental observations of welds in third-generation nickel-based superalloys

    Science.gov (United States)

    Naffakh-Moosavy, Homam

    2016-02-01

    The purpose of the present study is to introduce the weld quantitative solidification paths in the newly designed third-generation superalloys. The research has been conducted using both computational and experimental approaches. The model used the Scheil solidification relations to correlate the partitioning elements with their effects on the solidification paths. Accordingly, the k values were calculated for all the participating elements in the superalloy welds. The results of model demonstrated that these were very close to unity for austenite former elements, i.e. Ni, Co, Cr and Fe, while the other elements such as Ti, Nb and Mo displayed a significant tendency for segregation. The mathematical equations were calculated for weld solidification paths of superalloys. In all the welds, a remarkable segregation behaviour was observed, especially for Nb and Ti. The solidification path equations predicted type and amount of secondary phases. The solidification paths were compared with eutectic reactions ?, and ?, on the basis of the Ni-Ti-C and Ni-Nb-C ternary phase diagrams. Both the experimental measurements and microstructural observations of eutectics exhibited an appropriate accordance with the solidification paths obtained by model calculations.

  19. Constitutive behavior and processing maps of low-expansion GH909 superalloy

    Science.gov (United States)

    Yao, Zhi-hao; Wu, Shao-cong; Dong, Jian-xin; Yu, Qiu-ying; Zhang, Mai-cang; Han, Guang-wei

    2017-04-01

    The hot deformation behavior of GH909 superalloy was studied systematically using isothermal hot compression tests in a temperature range of 960 to 1040°C and at strain rates from 0.02 to 10 s-1 with a height reduction as large as 70%. The relations considering flow stress, temperature, and strain rate were evaluated via power-law, hyperbolic sine, and exponential constitutive equations under different strain conditions. An exponential equation was found to be the most appropriate for process modeling. The processing maps for the superalloy were constructed for strains of 0.2, 0.4, 0.6, and 0.8 on the basis of the dynamic material model, and a total processing map that includes all the investigated strains was proposed. Metallurgical instabilities in the instability domain mainly located at higher strain rates manifested as adiabatic shear bands and cracking. The stability domain occurred at 960-1040°C and at strain rates less than 0.2 s-1; these conditions are recommended for optimum hot working of GH909 superalloy.

  20. Microstructural response to heat affected zone cracking of prewelding heat-treated Inconel 939 superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, M.A., E-mail: mgonzalez@comimsa.com.mx [Facultad de Ingenieria Mecanica y Electrica (FIME-UANL), Av. Universidad s/n. Ciudad Universitaria, C.P.66451 San Nicolas de los Garza, N.L. (Mexico); Martinez, D.I., E-mail: dorairma@yahoo.com [Facultad de Ingenieria Mecanica y Electrica (FIME-UANL), Av. Universidad s/n. Ciudad Universitaria, C.P.66451 San Nicolas de los Garza, N.L. (Mexico); Perez, A., E-mail: betinperez@hotmail.com [Facultad de Ingenieria Mecanica y Electrica (FIME-UANL), Av. Universidad s/n. Ciudad Universitaria, C.P.66451 San Nicolas de los Garza, N.L. (Mexico); Guajardo, H., E-mail: hguajardo@frisa.com [FRISA Aerospace, S.A. de C.V., Valentin G. Rivero No. 200, Col. Los Trevino, C.P. 66150, Santa Caterina N.L. (Mexico); Garza, A., E-mail: agarza@comimsa.com [Corporacion Mexicana de Investigacion en Materiales S.A. de C.V. (COMIMSA), Ciencia y Tecnologia No.790, Saltillo 400, C.P. 25295 Saltillo Coah. (Mexico)

    2011-12-15

    The microstructural response to cracking in the heat-affected zone (HAZ) of a nickel-based IN 939 superalloy after prewelding heat treatments (PWHT) was investigated. The PWHT specimens showed two different microstructures: 1) spherical ordered {gamma} Prime precipitates (357-442 nm), with blocky MC and discreet M{sub 23}C{sub 6} carbides dispersed within the coarse dendrites and in the interdendritic regions; and 2) ordered {gamma} Prime precipitates in 'ogdoadically' diced cube shapes and coarse MC carbides within the dendrites and in the interdendritic regions. After being tungsten inert gas welded (TIG) applying low heat input, welding speed and using a more ductile filler alloy, specimens with microstructures consisting of spherical {gamma} Prime precipitate particles and dispersed discreet MC carbides along the grain boundaries, displayed a considerably improved weldability due to a strong reduction of the intergranular HAZ cracking associated with the liquation microfissuring phenomena. - Highlights: Black-Right-Pointing-Pointer Homogeneous microstructures of {gamma} Prime spheroids and discreet MC carbides of Ni base superalloys through preweld heat treatments. Black-Right-Pointing-Pointer {gamma} Prime spheroids and discreet MC carbides reduce the intergranular HAZ liquation and microfissuring of Nickel base superalloys. Black-Right-Pointing-Pointer Microstructure {gamma} Prime spheroids and discreet blocky type MC carbides, capable to relax the stress generated during weld cooling. Black-Right-Pointing-Pointer Low welding heat input welding speeds and ductile filler alloys reduce the HAZ cracking susceptibility.

  1. Welding Metallurgy of Nickel-Based Superalloys for Power Plant Construction

    Science.gov (United States)

    Tung, David C.

    Increasing the steam temperature and pressure in coal-fired power plants is a perpetual goal driven by the pursuit of increasing thermal cycle efficiency and reducing fuel consumption and emissions. The next target steam operating conditions, which are 760°C (1400°F) and 35 MPa (5000 psi) are known as Advanced Ultra Supercritical (AUSC), and can reduce CO2 emissions up to 13% but this cannot be achieved with traditional power plant construction materials. The use of precipitation-strengthened Nickel-based alloys (superalloys) is required for components which will experience the highest operating temperatures. The leading candidate superalloys for power plant construction are alloys 740H, 282, and 617. Superalloys have excellent elevated temperature properties due to careful microstructural design which is achieved through very specific heat treatments, often requiring solution annealing or homogenization at temperatures of 1100 °C or higher. A series of postweld heat treatments was investigated and it was found that homogenization steps before aging had no noticeable effect on weld metal microhardness, however; there were clear improvements in weld metal homogeneity. The full abstract can be viewed in the document itself.

  2. Modeling microstructure evolution in the delta process forging of superalloy IN718 turbine discs

    Science.gov (United States)

    Zhang, Haiyan; Zhang, Shihong; Cheng, Ming; Zhao, Zhong

    2013-05-01

    The microstructure development in the Delta Process (DP) forging of Superalloy IN718 turbine discs were predicted using the combined approach of axisymmetric finite element simulation and modeling for the dynamic recrystallization and grain growth. In order to establish the deformation constitutive equation and dynamic recrystallization models for the DP process of Superalloy IN718, the isothermal compression tests were carried out in the temperature range 950 to 1010 °C and strain rates range 0.001 to0.1s-1. Moreover, the isothermal heat treatment tests after hot deformation were conducted in the temperature range 950 to 1040°C to generate the grain growth model. The experimental results indicated the existence of the δ phase could make the activation energy of deformation increase. Furthermore, the existence of the δ phase could stimulate the occurrence of dynamic recrystallization, and the grain growth was restrained due to the pinning effect of δ phase. The predicted grain size and its distribution in the DP forging of Superalloy IN718 turbine discs were compared with the actual microstructures deformed by the hot die forging. It was found that the forging with uniform fine grains could be obtained by the application of DP process to the forging of the turbine disk, in which the alloy was pre-precipitated δ phase after the baiting in the original process.

  3. Investigation of Oxide Bifilms in Investment Cast Superalloy IN100: Part II. Characterization

    Science.gov (United States)

    Kaplan, Max A.; Fuchs, Gerhard E.

    2016-05-01

    Oxide bifilms are a proposed casting inclusion reported to have been observed in vacuum investment cast polycrystalline Ni-based superalloys. Ongoing research seeks to determine if current superalloy casting practices can result in the formation of oxide bifilms, and subsequently if it is possible to observe and characterize this phenomenon. The effect of casting atmosphere, turbulence, filtering, hot isostatic pressing, and heat treatment has been investigated to identify the critical parameters that have been reported to result in bifilm formation in Ni-based superalloy IN100. Scanning Auger microscopy (SAM), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM) were utilized to characterize samples from each casting condition. In situ ultrahigh vacuum Auger fractography did not indicate the presence of bifilms on the fracture behavior of IN100 in any processing condition. SAM analysis identified a sulfur-enriched monolayer on the surface of dendritic casting porosity, and identified heterogeneous Ti oxycarbide inclusions in air cast IN100. SEM analysis also indicated the presence of Ti oxycarbide inclusions in air cast IN100, and determined that these inclusion structures consist of fine blocky external M(Ti, Mo)C carbide enveloping an internal core of alumina. HR-TEM analysis indicated that none of the oxycarbide inclusion interfaces exist as discontinuous unbound interfaces, and that the internal alumina core is an ultra-fine polycrystalline structure.

  4. Study on Application of Grey Prediction Model in Superalloy MAR-247 Machining

    Directory of Open Access Journals (Sweden)

    Chen Shao-Hsien

    2015-01-01

    Full Text Available Superalloy MAR-247 is mainly applied in the space industry and die industry. With its characteristics of mechanical property, fatigue resistance, and high temperature corrosion resistance, therefore, it is mainly applied in machine parts of high temperature and corrosion resistance, such as turbine blades and rotor of the aeroengine and turbine assembly in the nuclear power plant. However, considering that its properties of high strength, low thermal conductivity, being difficult to soften, and work hardening may reduce the life of cutting-tool and weaken the surface accuracy, the study provided minimizing experiment occurring during milling process for superalloy material. As a statistical approach used to analyse experiment data, this study used GM(1,1 in the grey prediction model to conduct simulation and then predict and analyze its characteristics based on the experimental data, focusing on the tool life and surface accuracy. Moreover, with the superalloy machining parameters of the current effective application improved grey prediction model, it can decrease the errors, extend the tool life, and improve the prediction precision of surface accuracy.

  5. Directed self-assembly of a colloidal kagome lattice.

    Science.gov (United States)

    Chen, Qian; Bae, Sung Chul; Granick, Steve

    2011-01-20

    A challenging goal in materials chemistry and physics is spontaneously to form intended superstructures from designed building blocks. In fields such as crystal engineering and the design of porous materials, this typically involves building blocks of organic molecules, sometimes operating together with metallic ions or clusters. The translation of such ideas to nanoparticles and colloidal-sized building blocks would potentially open doors to new materials and new properties, but the pathways to achieve this goal are still undetermined. Here we show how colloidal spheres can be induced to self-assemble into a complex predetermined colloidal crystal-in this case a colloidal kagome lattice-through decoration of their surfaces with a simple pattern of hydrophobic domains. The building blocks are simple micrometre-sized spheres with interactions (electrostatic repulsion in the middle, hydrophobic attraction at the poles, which we call 'triblock Janus') that are also simple, but the self-assembly of the spheres into an open kagome structure contrasts with previously known close-packed periodic arrangements of spheres. This open network is of interest for several theoretical reasons. With a view to possible enhanced functionality, the resulting lattice structure possesses two families of pores, one that is hydrophobic on the rims of the pores and another that is hydrophilic. This strategy of 'convergent' self-assembly from easily fabricated colloidal building blocks encodes the target supracolloidal architecture, not in localized attractive spots but instead in large redundantly attractive regions, and can be extended to form other supracolloidal networks.

  6. Lattice Induced Transparency in Metasurfaces

    CERN Document Server

    Manjappa, Manukumara; Singh, Ranjan

    2016-01-01

    Lattice modes are intrinsic to the periodic structures and their occurrence can be easily tuned and controlled by changing the lattice constant of the structural array. Previous studies have revealed excitation of sharp absorption resonances due to lattice mode coupling with the plasmonic resonances. Here, we report the first experimental observation of a lattice induced transparency (LIT) by coupling the first order lattice mode (FOLM) to the structural resonance of a metamaterial resonator at terahertz frequencies. The observed sharp transparency is a result of the destructive interference between the bright mode and the FOLM mediated dark mode. As the FOLM is swept across the metamaterial resonance, the transparency band undergoes large change in its bandwidth and resonance position. Besides controlling the transparency behaviour, LIT also shows a huge enhancement in the Q-factor and record high group delay of 28 ps, which could be pivotal in ultrasensitive sensing and slow light device applications.

  7. Lattice models of ionic systems

    Science.gov (United States)

    Kobelev, Vladimir; Kolomeisky, Anatoly B.; Fisher, Michael E.

    2002-05-01

    A theoretical analysis of Coulomb systems on lattices in general dimensions is presented. The thermodynamics is developed using Debye-Hückel theory with ion-pairing and dipole-ion solvation, specific calculations being performed for three-dimensional lattices. As for continuum electrolytes, low-density results for simple cubic (sc), body-centered cubic (bcc), and face-centered cubic (fcc) lattices indicate the existence of gas-liquid phase separation. The predicted critical densities have values comparable to those of continuum ionic systems, while the critical temperatures are 60%-70% higher. However, when the possibility of sublattice ordering as well as Debye screening is taken into account systematically, order-disorder transitions and a tricritical point are found on sc and bcc lattices, and gas-liquid coexistence is suppressed. Our results agree with recent Monte Carlo simulations of lattice electrolytes.

  8. Lattice quantum chromodynamics practical essentials

    CERN Document Server

    Knechtli, Francesco; Peardon, Michael

    2017-01-01

    This book provides an overview of the techniques central to lattice quantum chromodynamics, including modern developments. The book has four chapters. The first chapter explains the formulation of quarks and gluons on a Euclidean lattice. The second chapter introduces Monte Carlo methods and details the numerical algorithms to simulate lattice gauge fields. Chapter three explains the mathematical and numerical techniques needed to study quark fields and the computation of quark propagators. The fourth chapter is devoted to the physical observables constructed from lattice fields and explains how to measure them in simulations. The book is aimed at enabling graduate students who are new to the field to carry out explicitly the first steps and prepare them for research in lattice QCD.

  9. Error Performance of Multidimensional Lattice Constellations-Part II: Evaluation over Fading Channels

    CERN Document Server

    Pappi, Koralia N; Chronis, Theodore N; Karagiannidis, George K

    2012-01-01

    This is the second part of a two-part series of papers, where the error performance of multidimensional lattice constellations with signal space diversity (SSD) is investigated. In Part I, following a novel combinatorial geometrical approach which is based on parallelotope geometry, we have presented an exact analytical expression and two closed-form bounds for the symbol error probability (SEP) in Additive White Gaussian Noise (AWGN). In the present Part II, we extend the analysis and present a novel analytical expression for the Frame Error Probability (FEP) of multidimensional lattice constellations over Nakagami-m fading channels. As the FEP of infinite lattices is lower bounded by the Sphere Lower Bound (SLB), we propose the Sphere Upper Bound (SUB) for block fading channels. Furthermore, two novel bounds for the FEP of multidimensional lattice constellations over block fading channels, named Multiple Sphere Lower Bound (MSLB) and Multiple Sphere Upper Bound (MSUB), are presented. The expressions for the...

  10. Solute atom migration in GH4169 superalloy under electrostatic fields

    Institute of Scientific and Technical Information of China (English)

    Yao Wang; Lei Wang; Yang Liu; Xiu Song; Bei-jiang Zhang; Jin-hui Du

    2013-01-01

    Electric field treatment (EFT) was applied on GH4169 alloy during aging at 500-800◦C to investigate the microstructure and property variation of the alloy under the action of EFT. The results demonstrate that the short-distance diff usion of Al, Ti, and Nb atoms can be accelerated by EFT, which results in the coarsening ofγ ? andγ ?? phases. Meanwhile, lattice distortion can be caused by the segregation of Fe and Cr atoms, owing to the vacancy flows migrating toward the charged surfaces of the alloy. Therefore, the alloy is hardened by the application of EFT, even if the strength of the alloy is partly reduced, which is caused by precipitation coarsening.

  11. Multilayer DNA Origami Packed on a Square Lattice

    Science.gov (United States)

    Ke, Yonggang; Douglas, Shawn M.; Liu, Minghui; Sharma, Jaswinder; Cheng, Anchi; Leung, Albert; Liu, Yan; Shih, William M.; Yan, Hao

    2009-01-01

    Molecular self-assembly using DNA as a structural building block has proven to be an efficient route to the construction of nanoscale objects and arrays of increasing complexity. Using the remarkable “scaffolded DNA origami” strategy, Rothemund demonstrated that a long single-stranded DNA from a viral genome (M13) can be folded into a variety of custom two-dimensional (2D) shapes using hundreds of short synthetic DNA molecules as staple strands. More recently, we generalized a strategy to build custom-shaped, three-dimensional (3D) objects formed as pleated layers of helices constrained to a honeycomb lattice, with precisely controlled dimensions ranging from 10 to 100 nm. Here we describe a more compact design for 3D origami, with layers of helices packed on a square lattice, that can be folded successfully into structures of designed dimensions in a one-step annealing process, despite the increased density of DNA helices. A square lattice provides a more natural framework for designing rectangular structures, the option for a more densely packed architecture, and the ability to create surfaces that are more flat than is possible with the honeycomb lattice. Thus enabling the design and construction of custom 3D shapes from helices packed on a square lattice provides a general foundational advance for increasing the versatility and scope of DNA nanotechnology. PMID:19807088

  12. Optimised Dirac operators on the lattice. Construction, properties and applications

    Energy Technology Data Exchange (ETDEWEB)

    Bietenholz, W. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik]|[Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

    2006-11-15

    We review a number of topics related to block variable renormalisation group transformations of quantum fields on the lattice, and to the emerging perfect lattice actions. We first illustrate this procedure by considering scalar fields. Then we proceed to lattice fermions, where we discuss perfect actions for free fields, for the Gross-Neveu model and for a supersymmetric spin model. We also consider the extension to perfect lattice perturbation theory, in particular regarding the axial anomaly and the quark gluon vertex function. Next we deal with properties and applications of truncated perfect fermions, and their chiral correction by means of the overlap formula. This yields a formulation of lattice fermions, which combines exact chiral symmetry with an optimisation of further essential properties. We summarise simulation results for these so-called overlap-hypercube fermions in the two-flavour Schwinger model and in quenched QCD. In the latter framework we establish a link to Chiral Perturbation Theory, both, in the p-regime and in the epsilon-regime. In particular we present an evaluation of the leading Low Energy Constants of the chiral Lagrangian - the chiral condensate and the pion decay constant - from QCD simulations with extremely light quarks. (orig.)

  13. Optimised Dirac operators on the lattice: construction, properties and applications

    Energy Technology Data Exchange (ETDEWEB)

    Bietenholz, Wolfgang [Humbolt-Universitaet zu Berlin (Germany). Inst. fuer Physik; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing (NIC)

    2006-12-15

    We review a number of topics related to block variable renormalisation group transformations of quantum fields on the lattice, and to the emerging perfect lattice actions. We first illustrate this procedure by considering scalar fields. Then we proceed to lattice fermions, where we discuss perfect actions for free fields, for the Gross-Neveu model and for a supersymmetric spin model. We also consider the extension to perfect lattice perturbation theory, in particular regarding the axial anomaly and the quark gluon vertex function. Next we deal with properties and applications of truncated perfect fermions, and their chiral correction by means of the overlap formula. This yields a formulation of lattice fermions, which combines exact chiral symmetry with an optimisation of further essential properties. We summarise simulation results for these so-called overlap-hypercube fermions in the two-flavour Schwinger model and in quenched QCD. In the latter framework we establish a link to Chiral Perturbation Theory, both, in the p-regime and in the e-regime. In particular we present an evaluation of the leading Low Energy Constants of the chiral Lagrangian - the chiral condensate and the pion decay constant - from QCD simulations with extremely light quarks. (author)

  14. Thermal conductivity of nickel superalloy MAR-M247

    OpenAIRE

    P. Jonšta; Koštial, P.; Jonšta, Z.; Vlčková, I.; T. Kulová

    2016-01-01

    The paper presents the narrow connection between γ’ phase dissolving and values of thermal conductivity. In annealing process the free space among γ’ particles (blocks) changes in certain cycle from fine to rough and back to fine. This is accompanied by decrease and subsequent increase of thermal conductivity as well as the sample density. The results of thermal conductivity coarse are supported by image analysis. Web of Science 55 3 422 420

  15. Investigation of Creep Feed Grinding Parameters and Heat treatment Effects on the Nickel-base Superalloys

    Institute of Scientific and Technical Information of China (English)

    Hasan Jamshidi; Sayed Ali Sadough Vanini; Alireza Attari

    2004-01-01

    The Nickel base Superalloys are the most famous complicated and useable of Superalloys to make hot zone components of the gas turbines. The complicated dimensional tolerances, specially at the root of the blade show importance of grinding processes at the production of blades root. The prediction of the effect of machining parameters on the soundness of component surface strengthening for reaching to a suitable surface finishing and avoiding from crack formation at the work part during machining operation often is not easy and feasible so needs to more industrial investigation.This research is about frame 5 blade designed by GE and made from Superalloy IN738LC has been investigated. The formation of a plastically deformed and heat affected zone during grinding of Superalloy IN738LC with a high depth of cut but slow work speed (creep feed grinding) was investigated. Parameters such as work speed, depth of cut and radial dressing speed have been considered as variables and their effects have been studied. During experimental performed, the voltage and current of motor measured and power and special energy calculated.Some samples heat-treated (of the 1176℃ for 1 hr under neutral argon gas and cooling rate of 15℃/min up to 537℃ and then air cooling) to study grains recrystallization. Other samples have been created from the roots of blades and then coated by Nickel to measure boundary layer micro-hardness. The results show that increasing work speed leads to increasing the use power. Increasing the depth of cut, by increasing material removal rate, and the radial dressing speed, by decreasing power, lead to decreasing special energy. The temperature created by grinding lead to decreasing plastic deformation and boundary layer formation. When the radial dressing speed changes from 1 to 0.6 μm/rev and other parameters are kept unchanged the roughness of surface increases and the special energy decreases. Sufficient dressing is very essential in limiting the width

  16. Oxidation behavior of Ni(Co)CrAlYHf(Si) coatings on DS superalloy at 1 150 ℃

    Institute of Scientific and Technical Information of China (English)

    HUANG Zhao-hui; TAN Yong-ning; ZHAO Xi-hong; LI Jian-ping; ZHANG Qiang

    2006-01-01

    Two Ni(Co)CrAlY coatings were deposited by EB-PVD method on a DS superalloy of Ni-Al-Cr-Co-W-Mo-Ta-Hf system. SEM, XEDS and XRD were used to study the oxidation behavior of the coatings. The two coatings show a good protection for the DS superalloy. The results of the isothermal oxidation test at 1 150 ℃ for 100 h show that the oxidation tendency obeys the parabolic law, and the oxidation rate constant Kp of the coated specimens decreases to about 1/3 of that for the bare superalloy. After oxidation, a continuous alumina-based scale is formed at the surfaces of the coated samples. Y2O3, NiO and SiO2 are also detectable in the oxide scale. A large number of Al in the coating is consumed due to high-temperature diffusion and oxidation reactions, and the NiAl phases in the coating are almost completely transformed to Ni3Al phases. For the Hf-bearing coating, some HfO2 particles exist at the interface between the coating and the substrate. Although internal oxidation occurs, the coating still shows a good adhesion with the superalloy substrate even after oxidation for 100 h. For the bare DS superalloy, after 100 h oxidation at 1 150 ℃, only discontinuous alumina-based oxide particles exist on the surface. Oxide spallation occurs for the bare alloy.

  17. Nuclear Physics from Lattice Quantum Chromodynamics

    CERN Document Server

    Savage, Martin J

    2015-01-01

    Quantum Chromodynamics and Quantum Electrodynamics, both renormalizable quantum field theories with a small number of precisely constrained input parameters, dominate the dynamics of the quarks and gluons - the underlying building blocks of protons, neutrons, and nuclei. While the analytic techniques of quantum field theory have played a key role in understanding the dynamics of matter in high energy processes, they encounter difficulties when applied to low-energy nuclear structure and reactions, and dense systems. Expected increases in computational resources into the exascale during the next decade will provide the ability to determine a range of important strong interaction processes directly from QCD using the numerical technique of Lattice QCD. This will complement the nuclear physics experimental program, and in partnership with new thrusts in nuclear many-body theory, will enable unprecedented understanding and refinement of nuclear forces and, more generally, the visible matter in our universe. In th...

  18. Nuclear Forces from Lattice Quantum Chromodynamics

    CERN Document Server

    Savage, Martin J

    2013-01-01

    A century of coherent experimental and theoretical investigations have uncovered the laws of nature that underly nuclear physics. The standard model of strong and electroweak interactions, with its modest number of input parameters, dictates the dynamics of the quarks and gluons - the underlying building blocks of protons, neutrons, and nuclei. While the analytic techniques of quantum field theory have played a key role in understanding the dynamics of matter in high energy processes, they encounter difficulties when applied to low-energy nuclear structure and reactions, and dense systems. Expected increases in computational resources into the exa-scale during the next decade will provide the ability to numerically compute a range of important strong interaction processes directly from QCD with quantifiable uncertainties using the technique of Lattice QCD. These calculations will refine the chiral nuclear forces that are used as input into nuclear many-body calculations, including the three- and four-nucleon ...

  19. Tensor renormalization group approach to two-dimensional classical lattice models.

    Science.gov (United States)

    Levin, Michael; Nave, Cody P

    2007-09-21

    We describe a simple real space renormalization group technique for two-dimensional classical lattice models. The approach is similar in spirit to block spin methods, but at the same time it is fundamentally based on the theory of quantum entanglement. In this sense, the technique can be thought of as a classical analogue of the density matrix renormalization group method. We demonstrate the method - which we call the tensor renormalization group method - by computing the magnetization of the triangular lattice Ising model.

  20. Irreversible stochastic processes on lattices

    Energy Technology Data Exchange (ETDEWEB)

    Nord, R.S.

    1986-01-01

    Models for irreversible random or cooperative filling of lattices are required to describe many processes in chemistry and physics. Since the filling is assumed to be irreversible, even the stationary, saturation state is not in equilibrium. The kinetics and statistics of these processes are described by recasting the master equations in infinite hierarchical form. Solutions can be obtained by implementing various techniques: refinements in these solution techniques are presented. Programs considered include random dimer, trimer, and tetramer filling of 2D lattices, random dimer filling of a cubic lattice, competitive filling of two or more species, and the effect of a random distribution of inactive sites on the filling. Also considered is monomer filling of a linear lattice with nearest neighbor cooperative effects and solve for the exact cluster-size distribution for cluster sizes up to the asymptotic regime. Additionally, a technique is developed to directly determine the asymptotic properties of the cluster size distribution. Finally cluster growth is considered via irreversible aggregation involving random walkers. In particular, explicit results are provided for the large-lattice-size asymptotic behavior of trapping probabilities and average walk lengths for a single walker on a lattice with multiple traps. Procedures for exact calculation of these quantities on finite lattices are also developed.

  1. Lattice topology dictates photon statistics

    CERN Document Server

    Kondakci, H Esat; Saleh, Bahaa E A

    2016-01-01

    Propagation of coherent light through a disordered network is accompanied by randomization and possible conversion into thermal light. Here, we show that network topology plays a decisive role in determining the statistics of the emerging field if the underlying lattice satisfies chiral symmetry. By examining one-dimensional arrays of randomly coupled waveguides arranged on linear and ring topologies, we are led to a remarkable prediction: the field circularity and the photon statistics in ring lattices are dictated by its parity -- whether the number of sites is even or odd, while the same quantities are insensitive to the parity of a linear lattice. Adding or subtracting a single lattice site can switch the photon statistics from super-thermal to sub-thermal, or vice versa. This behavior is understood by examining the real and imaginary fields on a chiral-symmetric lattice, which form two strands that interleave along the lattice sites. These strands can be fully braided around an even-sited ring lattice th...

  2. Lattice Boltzmann model for nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Xuan Yimin; Yao Zhengping [Nanjing University of Science and Technology, School of Power Engineering, Nanjing (China)

    2005-01-01

    A nanofluid is a particle suspension that consists of base liquids and nanoparticles and has great potential for heat transfer enhancement. By accounting for the external and internal forces acting on the suspended nanoparticles and interactions among the nanoparticles and fluid particles, a lattice Boltzmann model is proposed for simulating flow and energy transport processes inside the nanofluids. First, we briefly introduce the conventional lattice Boltzmann model for multicomponent systems. Then, we discuss the irregular motion of the nanoparticles and inherent dynamic behavior of nanofluids and describe a lattice Boltzmann model for simulating nanofluids. Finally, we conduct some calculations for the distribution of the suspended nanoparticles. (orig.)

  3. Localized structures in Kagome lattices

    Energy Technology Data Exchange (ETDEWEB)

    Saxena, Avadh B [Los Alamos National Laboratory; Bishop, Alan R [Los Alamos National Laboratory; Law, K J H [UNIV OF MASSACHUSETTS; Kevrekidis, P G [UNIV OF MASSACHUSETTS

    2009-01-01

    We investigate the existence and stability of gap vortices and multi-pole gap solitons in a Kagome lattice with a defocusing nonlinearity both in a discrete case and in a continuum one with periodic external modulation. In particular, predictions are made based on expansion around a simple and analytically tractable anti-continuum (zero coupling) limit. These predictions are then confirmed for a continuum model of an optically-induced Kagome lattice in a photorefractive crystal obtained by a continuous transformation of a honeycomb lattice.

  4. Lattice sums then and now

    CERN Document Server

    Borwein, J M; McPhedran, R C

    2013-01-01

    The study of lattice sums began when early investigators wanted to go from mechanical properties of crystals to the properties of the atoms and ions from which they were built (the literature of Madelung's constant). A parallel literature was built around the optical properties of regular lattices of atoms (initiated by Lord Rayleigh, Lorentz and Lorenz). For over a century many famous scientists and mathematicians have delved into the properties of lattices, sometimes unwittingly duplicating the work of their predecessors. Here, at last, is a comprehensive overview of the substantial body of

  5. Lattice Trace Operators

    Directory of Open Access Journals (Sweden)

    Brian Jefferies

    2014-01-01

    Full Text Available A bounded linear operator T on a Hilbert space ℋ is trace class if its singular values are summable. The trace class operators on ℋ form an operator ideal and in the case that ℋ is finite-dimensional, the trace tr(T of T is given by ∑jajj for any matrix representation {aij} of T. In applications of trace class operators to scattering theory and representation theory, the subject is complicated by the fact that if k is an integral kernel of the operator T on the Hilbert space L2(μ with μ a σ-finite measure, then k(x,x may not be defined, because the diagonal {(x,x} may be a set of (μ⊗μ-measure zero. The present note describes a class of linear operators acting on a Banach function space X which forms a lattice ideal of operators on X, rather than an operator ideal, but coincides with the collection of hermitian positive trace class operators in the case of X=L2(μ.

  6. Total Spinal Block after Thoracic Paravertebral Block.

    Science.gov (United States)

    Beyaz, Serbülent Gökhan; Özocak, Hande; Ergönenç, Tolga; Erdem, Ali Fuat; Palabıyık, Onur

    2014-02-01

    Thoracic paravertebral block (TPVB) can be performed with or without general anaesthesia for various surgical procedures. TPVB is a popular anaesthetic technique due to its low side effect profile and high analgesic potency. We used 20 mL of 0.5% levobupivacaine for a single injection of unilateral TPVB at the T7 level with neurostimulator in a 63 year old patient with co-morbid disease who underwent cholecystectomy. Following the application patient lost consciousness, and was intubated. Haemodynamic instability was normalised with rapid volume replacement and vasopressors. Anaesthetic drugs were stopped at the end of the surgery and muscle relaxant was antagonised. Return of mucle strenght was shown with neuromuscular block monitoring. Approximately three hours after TPVB, spontaneous breathing started and consciousness returned. A total spinal block is a rare and life-threatening complication. A total spinal block is a complication of spinal anaesthesia, and it can also occur after peripheral blocks. Clinical presentation is characterised by hypotension, bradicardia, apnea, and cardiac arrest. An early diagnosis and appropriate treatment is life saving. In this case report, we want to present total spinal block after TPVB.

  7. Design of Ni-base superalloys and MCrAlY coatings from first-principles and computational thermodynamics

    Science.gov (United States)

    Liu, Xuan

    This thesis explores the thermodynamics of Ni-base superalloys and metallic coatings used in the protection of these alloys. First, a thermodynamic description of the Nb-Re binary system is developed by means of the CALculation of PHAse Diagrams (CALPHAD) method supplemented by first-principles calculations based on density functional theory (DFT) and experimental data in the literature. In addition to terminal solution phases in the Nb-Re system, there are two intermetallic phases, sigma (sigma) and chi (chi), all modeled with sublattice models. Special quasi-random structures (SQS) are employed to mimic the random mixing of the bcc, hcp, and fcc solid solution phases from first-principles. Finite temperature thermodynamic properties of end-members and dilute mixing in each sublattice of the complex sigma and chi phases are predicted from first-principles calculations and the Debye-Gruneisen model. The utility of the Debye-Gruneisen model is then investigated with respect to its fitting parameter known as the scaling factor, and it is found that the prediction of finite-temperature properties can be improved by modification of this factor. This scaling factor is studied using bcc, fcc, hcp systems and the Mg-Zn binary system due to the abundance of thermodynamic data. Predicted Debye temperatures (thetaD), using a calculated scaling factor, show good agreement with experiments and improvements over the scaling factor derived by Moruzzi et al. Finite-temperature thermodynamic properties of intermetallics are investigated to show the efficiency and improved accuracy of the calculated scaling factor. However, for the intermetallic Mg2Zn11, the Debye-Gruneisen model cannot account for anomalous lattice dynamics at low temperatures. The calculated scaling factor is then used throughout the present work for finite-temperature predictions. Another missing piece of the literature includes the thermodynamics of Al-Co-Cr-Ni bond coat system used in the protection of

  8. Producing directed migration with correlated atoms in a tilted ac-driven lattice

    Science.gov (United States)

    Zheng, Yi; Yang, Shi-Jie

    2016-06-01

    The correlated atoms in a tilted optical lattice driven by an ac field are studied within the Hubbard model. By making use of both photon-assisted tunneling and coherent destructive tunneling effects, we can move a pair of strongly correlated atoms in the lattice via manipulating the global amplitude of the driving field. We propose a scheme for creating entanglement between the particle pair and a single particle through interacting oscillations. Our model may provide a new building block for investigating quantum computing and quantum information processing with ultracold atoms in optical lattices.

  9. Effect of Re Addition and Withdrawal Rate on the Solidification Behavior of Directionally Solidified Superalloy AM3

    Institute of Scientific and Technical Information of China (English)

    F.Long; Y.S.Yoo; S.M.Seo; T.Jin; Z.Q.Hu; C.Y.Jo

    2011-01-01

    The influence of Re addition and withdrawal rate on the solidification behavior of the first generation single crystal superalloy AM3 was investigated by directional solidification and quenching experiments. The primary dendrite arm spacing and eutectic volume fraction were measured from directionally solidified superalloy AM3 with different Re contents. It is found that the primary dendrite arm spacing is determined by the withdrawal rate, and Re does not influence on the value. The eutectic fraction increases with increasing Re addition. Partition coefficients of alloying elements were investigated with energy-dispersive X-ray spectrometry (EDS) analysis. The data was submitted to a statistical treatment to establish the solidification path, and the partition coefficients were measured by fitting the curve with a modified Scheil formula. It is shown that the addition of Re results in bigger microsegregation of alloying elements in directionally solidified AM3 superalloy.

  10. Evaluation of hot corrosion behaviour of HVOF sprayed NiCrAl coating on superalloys at 900 deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Mahesh, R.A. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, IIT Roorkee Campus, Roorkee 247667, Uttarakhand (India); Jayaganthan, R. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, IIT Roorkee Campus, Roorkee 247667, Uttarakhand (India)], E-mail: rjayafmt@iitr.ernet.in; Prakash, S. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, IIT Roorkee Campus, Roorkee 247667, Uttarakhand (India)

    2008-10-15

    In the present investigation, NiCrAl coating was deposited on Ni- and Fe-based superalloy substrates by using high velocity oxy-fuel (HVOF) process to study the hot corrosion behaviour in molten salt (Na{sub 2}SO{sub 4}-60% V{sub 2}O{sub 5}) environment at 900 deg. C under cyclic conditions. The mass gain measurements were performed after each cycle to establish the kinetics of corrosion using thermogravimetric technique. X-ray diffraction (XRD), scanning electron microscopy/energy dispersive spectroscopic analysis (SEM/EDS) and X-ray mapping techniques were used to analyse the corrosion products. The bare superalloys experienced higher weight gain. The NiCrAl-coated Superni 750 alloy (SN 750) provided a better protection among the coated superalloys investigated. The formation of oxides and spinels of nickel, chromium and aluminum may be contributing better resistance to hot corrosion.

  11. High-Temperature Oxidation Behavior of Two Nickel-Based Superalloys Produced by Metal Injection Molding for Aero Engine Applications

    Science.gov (United States)

    Albert, Benedikt; Völkl, Rainer; Glatzel, Uwe

    2014-09-01

    For different high-temperature applications like aero engines or turbochargers, metal injection molding (MIM) of superalloys is an interesting processing alternative. For operation at high temperatures, oxidation behavior of superalloys produced by MIM needs to match the standard of cast or forged material. The oxidation behavior of nickel-based superalloys Inconel 713 and MAR-M247 in the temperature interval from 1073 K to 1373 K (800 °C to 1100 °C) is investigated and compared to cast material. Weight gain is measured discontinuously at different oxidation temperatures and times. Analysis of oxidized samples is done via SEM and EDX-measurements. MIM samples exhibit homogeneous oxide layers with a thickness up to 4 µm. After processing by MIM, Inconel 713 exhibits lower weight gain and thinner oxide layers than MAR-M247.

  12. Generalized Block Failure

    DEFF Research Database (Denmark)

    Jönsson, Jeppe

    2015-01-01

    Block tearing is considered in several codes as a pure block tension or a pure block shear failure mechanism. However in many situations the load acts eccentrically and involves the transfer of a substantial moment in combination with the shear force and perhaps a normal force. A literature study...... yield lines around the block leads to simple interaction formulas similar to other interaction formulas in the codes.......Block tearing is considered in several codes as a pure block tension or a pure block shear failure mechanism. However in many situations the load acts eccentrically and involves the transfer of a substantial moment in combination with the shear force and perhaps a normal force. A literature study...

  13. Lattice radial quantization by cubature

    CERN Document Server

    Neuberger, Herbert

    2014-01-01

    Basic aspects of a program to put field theories quantized in radial coordinates on the lattice are presented. Only scalar fields are discussed. Simple examples are solved to illustrate the strategy when applied to the 3D Ising model.

  14. Areas on a Square Lattice

    Science.gov (United States)

    Wilby, Brian

    1974-01-01

    As an alternative to the usual method of counting squares to find the area of a plane shape, a method of counting lattice points (determined by vertices of a unit square) is proposed. Activities using this method are suggested. (DT)

  15. Nuclear models on a lattice

    CERN Document Server

    De Soto, F; Carbonell, J; Leroy, J P; Pène, O; Roiesnel, C; Boucaud, Ph.

    2007-01-01

    We present the first results of a quantum field approach to nuclear models obtained by lattice techniques. Renormalization effects for fermion mass and coupling constant in case of scalar and pseudoscalar interaction lagrangian densities are discussed.

  16. Baryon spectroscopy in lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Derek B. Leinweber; Wolodymyr Melnitchouk; David Richards; Anthony G. Williams; James Zanotti

    2004-04-01

    We review recent developments in the study of excited baryon spectroscopy in lattice QCD. After introducing the basic methods used to extract masses from correlation functions, we discuss various interpolating fields and lattice actions commonly used in the literature. We present a survey of results of recent calculations of excited baryons in quenched QCD, and outline possible future directions in the study of baryon spectra.

  17. Lattice QCD: A Brief Introduction

    Science.gov (United States)

    Meyer, H. B.

    A general introduction to lattice QCD is given. The reader is assumed to have some basic familiarity with the path integral representation of quantum field theory. Emphasis is placed on showing that the lattice regularization provides a robust conceptual and computational framework within quantum field theory. The goal is to provide a useful overview, with many references pointing to the following chapters and to freely available lecture series for more in-depth treatments of specifics topics.

  18. Berry phase in lattice QCD

    CERN Document Server

    Yamamoto, Arata

    2016-01-01

    We propose the lattice QCD calculation of the Berry phase which is defined by the ground state of a single fermion. We perform the ground-state projection of a single-fermion propagator, construct the Berry link variable on a momentum-space lattice, and calculate the Berry phase. As the first application, the first Chern number of the (2+1)-dimensional Wilson fermion is calculated by the Monte Carlo simulation.

  19. Transport in Sawtooth photonic lattices

    CERN Document Server

    Weimann, Steffen; Real, Bastián; Cantillano, Camilo; Szameit, Alexander; Vicencio, Rodrigo A

    2016-01-01

    We investigate, theoretically and experimentally, a photonic realization of a Sawtooth lattice. This special lattice exhibits two spectral bands, with one of them experiencing a complete collapse to a highly degenerate flat band for a special set of inter-site coupling constants. We report the ob- servation of different transport regimes, including strong transport inhibition due to the appearance of the non-diffractive flat band. Moreover, we excite localized Shockley surfaces states, residing in the gap between the two linear bands.

  20. Lattice Studies of Hyperon Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Richards, David G. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-04-01

    I describe recent progress at studying the spectrum of hadrons containing the strange quark through lattice QCD calculations. I emphasise in particular the richness of the spectrum revealed by lattice studies, with a spectrum of states at least as rich as that of the quark model. I conclude by prospects for future calculations, including in particular the determination of the decay amplitudes for the excited states.

  1. Lattice gauge theory for QCD

    Energy Technology Data Exchange (ETDEWEB)

    DeGrand, T. [Univ. of Colorado, Boulder, CO (United States). Dept. of Physics

    1997-06-01

    These lectures provide an introduction to lattice methods for nonperturbative studies of Quantum Chromodynamics. Lecture 1: Basic techniques for QCD and results for hadron spectroscopy using the simplest discretizations; lecture 2: Improved actions--what they are and how well they work; lecture 3: SLAC physics from the lattice-structure functions, the mass of the glueball, heavy quarks and {alpha}{sub s} (M{sub z}), and B-{anti B} mixing. 67 refs., 36 figs.

  2. Multifractal behaviour of -simplex lattic

    Indian Academy of Sciences (India)

    Sanjay Kumar; Debaprasad Giri; Sujata Krishna

    2000-06-01

    We study the asymptotic behaviour of resistance scaling and fluctuation of resistance that give rise to flicker noise in an -simplex lattice. We propose a simple method to calculate the resistance scaling and give a closed-form formula to calculate the exponent, , associated with resistance scaling, for any . Using current cumulant method we calculate the exact noise exponent for -simplex lattices.

  3. Optimal lattice-structured materials

    Science.gov (United States)

    Messner, Mark C.

    2016-11-01

    This work describes a method for optimizing the mesostructure of lattice-structured materials. These materials are periodic arrays of slender members resembling efficient, lightweight macroscale structures like bridges and frame buildings. Current additive manufacturing technologies can assemble lattice structures with length scales ranging from nanometers to millimeters. Previous work demonstrates that lattice materials have excellent stiffness- and strength-to-weight scaling, outperforming natural materials. However, there are currently no methods for producing optimal mesostructures that consider the full space of possible 3D lattice topologies. The inverse homogenization approach for optimizing the periodic structure of lattice materials requires a parameterized, homogenized material model describing the response of an arbitrary structure. This work develops such a model, starting with a method for describing the long-wavelength, macroscale deformation of an arbitrary lattice. The work combines the homogenized model with a parameterized description of the total design space to generate a parameterized model. Finally, the work describes an optimization method capable of producing optimal mesostructures. Several examples demonstrate the optimization method. One of these examples produces an elastically isotropic, maximally stiff structure, here called the isotruss, that arguably outperforms the anisotropic octet truss topology.

  4. Advances in Lattice Quantum Chromodynamics

    Science.gov (United States)

    McGlynn, Greg

    In this thesis we make four contributions to the state of the art in numerical lattice simulations of quantum chromodynamics (QCD). First, we present the most detailed investigation yet of the autocorrelations of topological observations in hybrid Monte Carlo simulations of QCD and of the effects of the boundary conditions on these autocorrelations. This results in a numerical criterion for deciding when open boundary conditions are useful for reducing these autocorrelations, which are a major barrier to reliable calculations at fine lattice spacings. Second, we develop a dislocation-enhancing determinant, and demonstrate that it reduces the autocorrelation time of the topological charge. This alleviates problems with slow topological tunneling at fine lattice spacings, enabling simulations on fine lattices to be completed with much less computational effort. Third, we show how to apply the recently developed zMobius technique to hybrid Monte Carlo evolutions with domain wall fermions, achieving nearly a factor of two speedup in the light quark determinant, the single most expensive part of the calculation. The dislocation-enhancing determinant and the zMobius technique have enabled us to begin simulations of fine ensembles with four flavors of dynamical domain wall quarks. Finally, we show how to include the previously-neglected G1 operator in nonperturbative renormalization of the DeltaS = 1 effective weak Hamiltonian on the lattice. This removes an important systematic error in lattice calculations of weak matrix elements, in particular the important K → pipi decay.

  5. The mechanisms and temperature dependence of superlattice stacking fault formation in the single-crystal superalloy PWA 1480

    Science.gov (United States)

    Milligan, Walter W.; Antolovich, Stephen D.

    1991-01-01

    The mechanism of the formation of superlattice staking faults in the single-crystal nickel-base superalloy PWA 1480 was investigated by observing deformation microstructures in the superalloy single crystals in the temperature range 20-1100 C. Results showed that, in addition to superlattice stacking faults observed after slow strain rate deformation at temperatures from 700 to 950 C, a high-density of superlattice staking faults formed after deformation at 200 C and below. The mechanisms of fault formation, which are different in the high- and the low-temperature regimes, are discussed.

  6. Solidification Behavior and Segregation of Re-containing Cast Ni-base Superalloy with Different Cr Content

    Institute of Scientific and Technical Information of China (English)

    Xiurong Guan; Enze Liu; Zhi Zheng; Yongsi Yu; Jian Tong; Yuchun Zhai

    2011-01-01

    The effect of chromium (Cr) on solidification and segregation behavior of Re-containing cast Ni-base superalloys was investigated by optical microscopy (OM), scanning electron microscopy (SEM) and electronic probe micro analysis (EPMA). The results show that Cr has significant effect on solidification and segregation behavior of Re-containing cast Ni-base superalloys. The liquidus and solidus of alloy decrease with increasing Cr in alloys. The segregation coefficient (K) of Mo increases and that of W and Re decreases gradually with increasing Cr element.

  7. A local factorization of the fermion determinant in lattice QCD

    CERN Document Server

    Cè, Marco; Schaefer, Stefan

    2016-01-01

    We introduce a factorization of the fermion determinant in lattice QCD with Wilson-type fermions that leads to a bosonic action local in the block fields. The interaction among gauge fields on distant blocks is mediated by multiboson fields located on the boundaries of the blocks. The resultant multiboson domain-decomposed hybrid Monte Carlo passes extensive numerical tests carried out by measuring standard gluonic observables. The combination of the determinant factorization and of the one of the propagator, that we put forward recently, paves the way for multilevel Monte Carlo integration in presence of fermions. We test this possibility by computing the disconnected correlator of two flavor-diagonal pseudoscalar densities, and we observe a significant increase of the signal-to-noise ratio due to a two-level integration.

  8. A local factorization of the fermion determinant in lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Ce, Marco [Scuola Normale Superiore, Pisa (Italy); INFN, Pisa (Italy); Giusti, Leonardo [Milano-Bicocca Univ. (Italy). Dipartimento di Fisica; INFN, Milano-Bicocca (Italy); Schaefer, Stefan [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

    2016-09-15

    We introduce a factorization of the fermion determinant in lattice QCD with Wilson-type fermions that leads to a bosonic action which is local in the block fields. The interaction among gauge fields on distant blocks is mediated by multiboson fields located on the boundaries of the blocks. The resultant multiboson domain-decomposed hybrid Monte Carlo passes extensive numerical tests carried out by measuring standard gluonic observables. The combination of the determinant factorization and of the one of the propagator, that we put forward recently, paves the way for multilevel Monte Carlo integration in the presence of fermions. We test this possibility by computing the disconnected correlator of two flavor-diagonal pseudoscalar densities, and we observe a significant increase of the signal-to-noise ratio due to a two-level integration.

  9. BLOCK H-MATRICES AND SPECTRUM OF BLOCK MATRICES

    Institute of Scientific and Technical Information of China (English)

    黄廷祝; 黎稳

    2002-01-01

    The block H-matrices are studied by the concept of G-functions, several concepts of block matrices are introduced. Equivalent characters of block H-matrices are obtained. Spectrum localizations claracterized by Gfunctions for block matrices are got.

  10. A lexicographic shellability characterization of geometric lattices

    CERN Document Server

    Davidson, Ruth

    2011-01-01

    Geometric lattices are characterized as those finite, atomic lattices such that every atom ordering induces a lexicographic shelling given by an edge labeling known as a minimal labeling. This new characterization fits into a similar paradigm as McNamara's characterization of supersolvable lattices as those lattices admitting a different type of lexicographic shelling, namely one in which each maximal chain is labeled with a permutation of {1,...,n}. Geometric lattices arise as the intersection lattices of central hyperplane arrangements and more generally as the lattices of flats for matroids.

  11. Block TERM factorization of block matrices

    Institute of Scientific and Technical Information of China (English)

    SHE Yiyuan; HAO Pengwei

    2004-01-01

    Reversible integer mapping (or integer transform) is a useful way to realize Iossless coding, and this technique has been used for multi-component image compression in the new international image compression standard JPEG 2000. For any nonsingular linear transform of finite dimension, its integer transform can be implemented by factorizing the transform matrix into 3 triangular elementary reversible matrices (TERMs) or a series of single-row elementary reversible matrices (SERMs). To speed up and parallelize integer transforms, we study block TERM and SERM factorizations in this paper. First, to guarantee flexible scaling manners, the classical determinant (det) is generalized to a matrix function, DET, which is shown to have many important properties analogous to those of det. Then based on DET, a generic block TERM factorization,BLUS, is presented for any nonsingular block matrix. Our conclusions can cover the early optimal point factorizations and provide an efficient way to implement integer transforms for large matrices.

  12. Morphology and phase diagram of comb block copolymer Am+1(BC)m.

    Science.gov (United States)

    Jiang, Zhibin; Wang, Rong; Xue, Gi

    2009-05-28

    The morphologies and the phase diagram of comb copolymer Am+1(BC)m are investigated by the self-consistent field theory. By changing the volume fractions of the blocks, the interaction parameters between the different blocks, and the side chain number, nine phases are found, including the two-colored lamellar phase, three-colored lamellar phase, hexagonal lattice phase, core shell hexagonal lattice phase, two interpenetrating tetragonal lattice, core shell tetragonal lattice, lamellar phase with beads inside, lamellar phase with alternating beads, and disordered phase. The phase diagrams are constructed for Am+1(BC)m with different side chain numbers of m=1, 2, 3, and 5. Due to the asymmetric topology of comb copolymer Am+1(BC)m, the phases and the diagrams are very different from linear ABC triblock copolymer or star ABC triblock copolymer. When the volume fraction of one of the blocks is the domination, the (core shell) hexagonal phase or two interpenetrating tetragonal lattice can form, depending on which block dominates and the interaction between the blocks. The (core shell) hexagonal phase easily forms at the corner of the block A (fA>or=0.5). The side chain number m affects the phase diagram largely due to the fact that the architecture of a comb copolymer is not invariant under the interchange between the three different monomers. Due to the connectivity of the blocks B and the inner blocks A, Am+1(BC)m comb copolymers with the longer main chain A or longer side chain with short block C, i.e., longer block B, are difficult to phase separate. The results are helpful to design nano- or biomaterials with complex architecture or tailor the phase behavior of comb copolymers.

  13. 3-sheet structure of Inconel 718 superalloy processed by LBW/SPF and its load response

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The 3-sheet structure of Inconel 718 superalloy will be used in flying vehicles as heat resisting and shielding structure due to its lightweight, high strength and stiffness. The 3-sheet structure of Inconel 718 superalloy processed by LBW/SPF (laser beam welding/superplastic forming) technology exhibited good configuration and uniform thickness distribution. The LBW parameters for 3-sheet structure were as follows: Pulse frequency was 32 Hz, impulse duration 3 ms, peak power per pulse 4500 W, and welding speed 180 mm/min. The SPF parameters were as follows: Temperature T=965 ℃, forming pressure P=4.2 MPa, and forming time t=130 min. The microstructure in weld fusion zone was consti- tuted of austenite dendritics and Laves phase precipitated in interdendritics. After the SPF process, austenite dendritics in the weld fusion became coarser and most of Laves phases were dissolved and turned into δ precipitated phase, but a few of Laves phases were still reserved. And Nb concentration in dendritics increased to 5.42% compared to 2.82% in as-weld condition. Weld metal Vickers-hardness increased from 331.63 in as-weld condition to 391.74 in post-SPF condition which was closed to the base material Vickers-hardness of post-SPF. Grain size of base material grew slightly and an amount of precipitated phase appeared in the base material undergoing SPF process. The tensile test results of base material showed that tensile strength increased obviously and the ductility decreased slightly after SPF process. Load response test results indicated that the 3-sheet structure possessed good resistance to compression and bending load. Accordingly, the LBW/SPF technology is an appropriate forming technique for the 3-sheet structure of Inconel 718 superalloy.

  14. 3-sheet structure of Inconel 718 superalloy processed by LBW/SPF and its load response

    Institute of Scientific and Technical Information of China (English)

    QU FengSeng; ZHANG KaiFeng

    2009-01-01

    The 3-sheet structure of Inconel 718 superalloy will be used in flying vehicles as heat resisting and shielding structure due to its lightweight,high strength and stiffness.The 3-sheet structure of Inconel 718 superalloy processed by LBW/SPF(laser beam welding/superplastic forming)technology exhibited good configuration and uniform thickness distribution.The LBW parameters for 3-sheet structure were as follows:Pulse frequency was 32 Hz,impulse duration 3 ms,peak power per pulse 4500 W,and welding speed 180 mm/min.The SPF parameters were as follows:Temperature T=965℃,forming pressure P=-4.2 MPa,and forming time t=130 min.The microstructure in weld fusion zone was constituted of austenite dendritics and Laves phase precipitated in interdendritics.After the SPF process,austenite dendritics in the weld fusion became coarser and most of Laves phases were dissolved and turned into δprecipitated phase,but a few of Laves phases were still reserved.And Nb concentration in dendritics increased to 5.42% compared to 2.82% in as-weld condition.Weld metal Vickers-hardness increased from 331.63 in as-weld condition to 391.74 in post-SPF condition which was closed to the base material Vickers-hardness of post-SPF.Grain size of base material grew slightly and an amount of precipitated phase appeared in the base material undergoing SPF process.The tensile test results of base material showed that tensile strength increased obviously and the ductility decreased slightly after SPF process.Load response test results indicated that the 3-sheet structure possessed good resistance to compression and bending load.Accordingly,the LBW/SPF technology is an appropriate forming technique for the 3-sheet structure of inconel 718 superalloy.

  15. Lesson Thirteen Trifascicular Block

    Institute of Scientific and Technical Information of China (English)

    鲁端; 王劲

    2005-01-01

    @@ A complete trifascicular block would result in complete AV block. The idio ventricular rhythm has a slower rate and a wide QRS complex because the pacemaker is located at the peripheral part of the conduction system distal to the sites of the block1. Such a rhythm may be difficult to differentiate from bifascicular or bundle branch block combined with complete block at a higher level such as the AV node or His bundle2. Besides a slower ventricular rate, a change in the morphology of the QRS complex from a previous known bifascicular pattern would be strongly suggestive of a trifascicular origin of the complete AV block3. A His bundle recording is required for a definitive diagnosis, however.

  16. Embedded Lattice and Properties of Gram Matrix

    Directory of Open Access Journals (Sweden)

    Futa Yuichi

    2017-03-01

    Full Text Available In this article, we formalize in Mizar [14] the definition of embedding of lattice and its properties. We formally define an inner product on an embedded module. We also formalize properties of Gram matrix. We formally prove that an inverse of Gram matrix for a rational lattice exists. Lattice of Z-module is necessary for lattice problems, LLL (Lenstra, Lenstra and Lov´asz base reduction algorithm [16] and cryptographic systems with lattice [17].

  17. Comparison of measured and calculated thermophysical properties of nickel super-alloys

    Directory of Open Access Journals (Sweden)

    A. Kalup

    2016-07-01

    Full Text Available Three real grades of nickel super-alloys (IN 713LC, IN 738LC and IN 792-5A were investigated and values of temperatures of phase transformations and latent heats of melting were obtained. All investigated quantities are very important for thermodynamic and kinetic modelling. Moreover, these data are also valuable for a lot of software used for technological processes modelling. Experimental values were obtained using Differential Thermal Analysis (DTA measurements. Calculations were performed using Thermo-Calc 3.1 software with the use of three different databases (SSOL5, TTNI8 and TCNI6. Comparison and discussion of experimental and calculated data was performed.

  18. Processing and characterization of Nickel-base superalloy micro-components and films for MEMS applications

    Science.gov (United States)

    Burns, Devin E.

    Microelectromechanical (MEMS) devices are not capable of withstanding harsh operating environments, which may include high temperatures, pressures and corrosive agents. Ni-base superalloys have been used successfully in the hot stages of jet turbine engines despite the presence of these conditions. In my thesis work, I developed two techniques compatible with micro-processing methods to produce Ni-base superalloy micro-components for MEMS applications. The mechanical properties of these materials were accessed at room and elevated temperatures. Microstructural studies were performed, linking microstructural features to mechanical properties. The first technique modified LIGA Ni (LIGA is a German acronym for lithography, electroplating and molding) microtensile specimens using a vapor phase aluminization process. A subsequent homogenization heat treatment produced a two phase Ni-Ni3A1 microstructure characteristic of modern Ni-base superalloys. Al composition was used to tailor both the precipitate size and volume fraction. Aluminized LIGA Ni micro-components exhibited room temperature yield and ultimate strengths 3 to 4 times LIGA Ni micro-components subject to the same heat treatment. The second technique involved sputtering a commercial Ni-base superalloy, Haynes 718, to produce thick sputtered foils (up to 20 gam) on silicon and brass substrates. The as-deposited foils were nanocrystalline solid solutions with chemical compositions similar to the bulk material. Foils subject to ageing heat treatments exhibited unique precipitation mechanisms and good thermal stability. Strengths as high as 750 MPa at 700°C were observed with several percent ductility. This is a significant improvement over state of the art metallic MEMS materials. Furthermore, a new high temperature microtensile testing technique was developed. The technique embeds a displacement based force sensor into the hot zone of a furnace. This arrangement ensures temperature uniformity during testing

  19. Nucleation mechanisms of dynamic recrystallization in Inconel 625 superalloy deformed with different strain rates

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The effects of strain rates on the hot working characteristics and nucleation mechanisms of dynamic recrystallization (DRX) were studied by optical microscopy and electron backscatter diffraction (EBSD) technique. Hot compression tests were conducted using a Gleeble-1500 simulator at a true strain of 0.7 in the temperature range of 1000 to 1150 °C and strain rate range of 0.01 to 10.00 s-1. It is found that the size and volume fraction of the DRX grains in hot-deformed Inconel 625 superalloy firstly decreas...

  20. Effects of recrystallization on the low cycle fatigue behavior of directionally solidified superalloy DZ40M

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yang; WANG Lei; LI Hongyun; YU Teng; LIU Yang

    2008-01-01

    The effects of recrystallization on low cycle fatigue behavior were investigated on directionally solidified Co-base superalloy DZAOM.Optical microscopy and SEM were used to examine the mierostructure and fracture surface of the specimens.The mechanical testing results demonstrated that the low cycle fatigue property of DZ40M significantly decreased with the partial reerystallization.Fatigue cracks initiate near the carbides and the grain boundaries with slip-bands.Both the fatigue crack initiation and propagation can be accelerated with the occurrences of recrystallized grain boundaries.

  1. Nucleation mechanism of a nickel-base superalloy during dynamic recrystallization

    Institute of Scientific and Technical Information of China (English)

    Shuai WANG; Lei WANG; Yang LIU; Guohua XU; Beijiang ZHANG; Guangpu ZHAO

    2011-01-01

    Hot compression test was carried out at 1000 ℃ to investigate the dynamic recrystallization nucleation mechanism of a nickel-base superalloy.It was found that the bulging of original grain boundaries was inhibited by carbides and deformation twins at the boundaries.Recrystallized nuclei evolved from the subgrains of dislocation reconfiguration along original grain boundaries,and the growth of the potential nuclei was carried out by the coalescence of subgrains.The necklace structure of recrystallized grains along original grain boundaries was attributed to the strain gradient from grain boundary to grain interior.

  2. Computational Design of Creep-Resistant Alloys and Experimental Validation in Ferritic Superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Liaw, Peter

    2014-12-31

    A new class of ferritic superalloys containing B2-type zones inside parent L21-type precipitates in a disordered solid-solution matrix, also known as a hierarchical-precipitate strengthened ferritic alloy (HPSFA), has been developed for high-temperature structural applications in fossil-energy power plants. These alloys were designed by the addition of the Ti element into a previously-studied NiAl-strengthened ferritic alloy (denoted as FBB8 in this study). In the present research, systematic investigations, including advanced experimental techniques, first-principles calculations, and numerical simulations, have been integrated and conducted to characterize the complex microstructures and excellent creep resistance of HPSFAs. The experimental techniques include transmission-electron microscopy, scanningtransmission- electron microscopy, neutron diffraction, and atom-probe tomography, which provide detailed microstructural information of HPSFAs. Systematic tension/compression creep tests revealed that HPSFAs exhibit the superior creep resistance, compared with the FBB8 and conventional ferritic steels (i.e., the creep rates of HPSFAs are about 4 orders of magnitude slower than the FBB8 and conventional ferritic steels.) First-principles calculations include interfacial free energies, anti-phase boundary (APB) free energies, elastic constants, and impurity diffusivities in Fe. Combined with kinetic Monte- Carlo simulations of interdiffusion coefficients, and the integration of computational thermodynamics and kinetics, these calculations provide great understanding of thermodynamic and mechanical properties of HPSFAs. In addition to the systematic experimental approach and first-principles calculations, a series of numerical tools and algorithms, which assist in the optimization of creep properties of ferritic superalloys, are utilized and developed. These numerical simulation results are compared with the available experimental data and previous first

  3. Phase transformation and liquid density redistribution during solidification of Ni-based superalloy Inconel 718

    Directory of Open Access Journals (Sweden)

    Wang Ling

    2012-08-01

    Full Text Available The influences of chemical segregation and phase transformation on liquid density variation during solidification of Ni-based supperalloy Inconel 718 were investigated using SEM and EDS. It was found that significant segregation in liquid prompts high Nb phase to precipitate directly from liquid, which results in the redistribution of alloy elements and liquid density in their vicinity. The term “inter-precipitate liquid density” is therefore proposed and this concept should be applied to determine the solidification behavior of superalloy Inconel 718.

  4. High Temperature Oxidation and Electrochemical Studies on Novel Co-Base Superalloys

    OpenAIRE

    Klein, Leonhard

    2013-01-01

    Isothermal oxidation in air was carried out on novel γ'-strengthened Cobalt-base superalloys of the system Co–Al–W–B. After fast initial oxide formation, a multi-layered structure establishes, consisting of an outer cobalt oxide layer, a middle spinel-containing layer, and an inner Al2O3-rich region. Ion diffusion in outward direction is hindered by the development of Al2O3, that can be either present as a continuous and protective layer or as a discontinuous Al2O3-rich area without comparabl...

  5. Analysis of the solidified structure of rheocast and VADER processed nickel-base superalloy

    Science.gov (United States)

    Apelian, D.; Cheng, J.-J. A.

    1986-01-01

    Conventional 'ingot' processing of highly alloyed compositions results in a cast product which suffers from extensive macrosegregation, hot tears, and heterogeneities. By controlling the solidification journey, one can produce a fine grained cast product. This is achieved by manipulating the melt in the mushy zone. Rheocasting and vacuum arc double electrode remelting (VADER) are two such technologies where the melt is processed in the mushy zone. IN-100, a nickel based superalloy, was rheocast as well as VADER processed. The resultant cast structures are analyzed, compared and discussed both onmicro- and macrostructural levels. The effect of the rheocast processing variables (stirring seed, time and temperature) on the cast microstructure are also discussed.

  6. Precipitation in Powder Metallurgy, Nickel Base Superalloys: Review of Modeling Approach and Formulation of Engineering (Postprint)

    Science.gov (United States)

    2016-12-01

    such as those of interest here, the work of Campbell et al. [60] and Semiatin et al. [50] suggests that Cr diffusion is rate limiting in γ-γ...the work of Campbell et al. [60]. In addition, w(f ) was taken from the research of Voorhees and Glicksman [20], and σ was assumed to be 23 mJ/m2 per...2104) Alloying-element loss during high-temperature processing of a nickel-base superalloy. Metall Mater Trans A 45:962–979 60. Campbell CE, Zhao JC

  7. Creep, Fatigue and Environmental Interactions and Their Effect on Crack Growth in Superalloys

    Science.gov (United States)

    Telesman, J.; Gabb, T. P.; Ghosn, L. J.; Smith, T.

    2017-01-01

    Complex interactions of creep/fatigue/environment control dwell fatigue crack growth (DFCG) in superalloys. Crack tip stress relaxation during dwells significantly changes the crack driving force and influence DFCG. Linear Elastic Fracture Mechanics, Kmax, parameter unsuitable for correlating DFCG behavior due to extensive visco-plastic deformation. Magnitude of remaining crack tip axial stresses controls DFCG resistance due to the brittle-intergranular nature of the crack growth process. Proposed a new empirical parameter, Ksrf, which incorporates visco-plastic evolution of the magnitude of remaining crack tip stresses. Previous work performed at 704C, extend the work to 760C.

  8. Metallurgical instabilities during the high temperature low cycle fatigue of nickel-base superalloys

    Science.gov (United States)

    Antolovich, S. D.; Jayaraman, N.

    1983-01-01

    An investigation is made of the microstructural instabilities that affect the high temperature low cycle fatigue (LCF) life of nickel-base superalloys. Crack initiation processes, provoked by the formation of carbides and the coarsening of the grains of the material at high temperatures are discussed. Experimental results are examined, and it is concluded that LCF behavior can be understood more fully only if details of the material and its dynamic behavior at high temperatures are considered. The effects of high stress, dislocation debris, and increasing environmental damage on the life of the alloy are discussed.

  9. Effects of secondary precipitation on recrystallization in Co-base superalloy DZ40M

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yang; WANG Lei; YU Teng; SONG Xiu

    2006-01-01

    A series of experimental studies were conducted on the recrystallization of directionally solidified cobalt-base superalloy DZ40M. It is found that the secondary M23C6 precipitation influences the size and shape of the recrystal grains. When the annealing temperature is below 1 473 K, a large amount of the fine secondary M23C6 precipitations are distributed around the primary carbides, and such carbides impede the movement of grain boundary because the effect, the size and shape of recrystal grains become irregularly. When the temperature exceeds 1 473 K, the recrystal grains grow rapidly due to the dissolved secondary M23C6 precipitation.

  10. Surface Modification Concepts for Enhancement of the High-Temperature Corrosion Resistance of Gas Turbine Superalloys,

    Science.gov (United States)

    1980-12-01

    in the Marine Environment, 1974, NTIS-MCIC-75-27. 23. Restall , J.E., Metallurgia, 1979, Nov., 676. 24. Coward, G.W. and Boone, D.H., Oxidation of...J.C. and Ault, G.M., 3rd Int. Symposium on Superalloys; Metall. and Manufacture, 1976, AIHE. 31. Restall , J.E., Institute of Metals/CAPA/ICT...a function of time for various alloys and coatings (after Restall [23]). TEMPERATURE, 0C 300 400 600 800 1000 A K =C(Ni) X P12 /C(NiQ0) 10-20 ED E N0

  11. Analysis of Grain Boundary Character in a Fine-Grained Nickel-Based Superalloy 718

    Science.gov (United States)

    Araujo, L. S.; dos Santos, D. S.; Godet, S.; Dille, J.; Pinto, A. L.; de Almeida, L. H.

    2014-11-01

    In the current work, sheets of superalloy 718 were processed via thermomechanical route by hot and cold rolling, followed by annealing below the δ phase solvus temperature and precipitation hardening to optimum strength. Grain boundary character distribution throughout the processing was mapped via EBSD and its evolution discussed. The results show that it is possible to process the alloy to a fine grain size obtaining concomitantly a considerably high proportion of special boundaries Σ3, Σ9, and Σ27. The precipitation of δ phase presented a strong grain refining role, without significantly impairing the twinning mechanism and, consequently, the Σ3, Σ9, and Σ27 boundary formations.

  12. Preparation, Structure and Mechanical Properties of Nickel Based Porous Spherical Superalloy

    Institute of Scientific and Technical Information of China (English)

    MI Guo-fa; LI Hong-yu; LIU Xiang-yu; WANG Kuang-fei

    2009-01-01

    The porous superalloy materials with hollow spherical pores were fabricated by using metal powder sintering process.The scanning electron microscope (SEM) observation was applied to the test samples and it revealed that the pores of the porous material exhibited a uniform distribution and the apet;tures were of same size in principle.The sintering necks appeared between adjacent particles on metal skeleton after sintering.The mechanical properties of the test samples were analyzed and the result showed that this kind of materials possessed excellent energy absorption capability,and the compression resistance decreased with increasing the porosity and aperture.

  13. Numerical Simulation of Vacuum Heat Treatment Thermal Hysteresis Time of GH4169 Superalloy Workpiece

    Institute of Scientific and Technical Information of China (English)

    WANGMing-wei; ZHANGLi-wen; JIANGGuo-dong; ZHANGFan-yun; LiChen-hui; ZHANGLi-sheng; ZHANGZun-li

    2004-01-01

    A nonlinear finite element model of vacuum heat treatment process was developed. In this model, influence of many factors, such as nonlinear heat radiation, temperature-dependent thermal physical properties of material are considered. The temperature field of GH4169 alloy workpiece during vacuum heat treatment process was calculated using finite element software MSC.Marc, and the thermal hysteresis time of the workpiece was predicted. An experiment of vacuum heat treatment of GH4169 superalloy workpiece was carried out to verify the calculation. The experimental results of temperature profile agree well with the simulated results. This work lays a theoretical foundation for optimizing technical parameter of vacuum heat treatment process.

  14. Homogenization kinetics of a nickel-based superalloy produced by powder bed fusion laser sintering

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fan; Levine, Lyle E.; Allen, Andrew J.; Campbell, Carelyn E.; Lass, Eric A.; Cheruvathur, Sudha; Stoudt, Mark R.; Williams, Maureen E.; Idell, Yaakov

    2017-04-01

    Additively manufactured (AM) metal components often exhibit fine dendritic microstructures and elemental segregation due to the initial rapid solidification and subsequent melting and cooling during the build process, which without homogenization would adversely affect materials performance. In this letter, we report in situ observation of the homogenization kinetics of an AM nickel-based superalloy using synchrotron small angle X-ray scattering. The identified kinetic time scale is in good agreement with thermodynamic diffusion simulation predictions using microstructural dimensions acquired by ex situ scanning electron microscopy. These findings could serve as a recipe for predicting, observing, and validating homogenization treatments in AM materials.

  15. Primary and secondary dendrite spacing of Ni-based superalloy single crystals

    Directory of Open Access Journals (Sweden)

    SLOBODANKA KOSTIC

    2009-01-01

    Full Text Available Ni-based superalloy single crystals were grown by different methods (gradient method and Bridgman technique with spontaneous nucleation and with seed. In all crystal growth experiments using the Bridgman technique, the temperature gradient along the vertical furnace axes was constant (G = 33.5 °C/cm. The obtained single crystals were cut, mechanical and chemical polished, and chemically etched. Using a metallographic microscope, the spacing of the primary and secondary dendrites was investigated. The dendrite arm spacing (DAS was determined using a Quantimet 500 MC. The obtained results are discussed and compared with published data.

  16. Inertia Friction Welding of Dissimilar Superalloys Mar-M247 and LSHR

    Science.gov (United States)

    Senkov, Oleg N.; Mahaffey, David W.; Semiatin, S. Lee; Woodward, Christopher

    2014-11-01

    The solid state inertia friction welding (IFW) process was used for the first time to join two dissimilar Ni-based superalloys, LSHR, a powder metallurgy alloy, and Mar-M247, a directionally solidified alloy. Extensive studies of the microstructure, phase composition, re-distribution of the alloying elements between the welded alloys, microhardness, and welding defects were conducted at different distances from the weld interface, and the results were correlated with the loading and friction conditions during IFW. Possible reasons leading to the formation of the welding defects were discussed and directions for the further improvement of the quality of the IFW of these two dissimilar alloys were outlined.

  17. Characterization of Casting Defects in Typical Castings of a Directionally Solidified Superalloy

    Science.gov (United States)

    1979-08-01

    used to evaluate grain misorientation effects in D.S. MAR - M247 superalloy (17). Scatter of this nature has been observed previously in equiaxed cast...found associated with the fracture surfaces In the previous study on tje effect of off-axis grain growth on cylindrical cast bars of D.S. MAR - M247 , 1800...significant that no instances of failures associated with emergent grains were observed in the MAR - M247 study. In the present investigation of PWA 1422, no

  18. Evaluation of Heat Checking and Washout of Heat Resistant Superalloys and Coatings for Die inserts

    Energy Technology Data Exchange (ETDEWEB)

    David Schwam; John F. Wallace; Yulong Zhu; Edward Courtright; Harold Adkins

    2005-01-30

    This project had two main objectives: (1) To design, fabricate and run a full size test for evaluating soldering and washout in die insert materials. This test utilizes the unique capabilities of the 350 Ton Squeeze Casting machine available in the Case Meal Casting Laboratory. Apply the test to evaluate resistance of die materials and coating, including heat resistant alloys to soldering and washout damage. (2) To evaluate materials and coatings, including heat resistant superalloys, for use as inserts in die casting of aluminum alloys.

  19. Investigation of delamination mechanisms during a laser drilling on a cobalt-base superalloy

    OpenAIRE

    Girardot, Jérémie; Schneider, Matthieu; Berthe, Laurent; FAVIER, Véronique

    2013-01-01

    International audience; Temperatures in the high pressure chamber of aircraft engines are continuously increasing to improve the engine efficiency. As a result, constitutive materials such as cobalt and nickel-base superalloys need to be thermally protected. The first protection is a ceramic thermal barrier coating (TBC) cast on all the hot gas-exposed structure. The second protection is provided by a cool air layer realized by the use of a thousand of drills on the parts where a cool air is flo...

  20. Cobalt-based superalloy layers deposited on X38CrMoV5 steel base metal by explosion cladding process

    OpenAIRE

    Langlois, Laurent; Bigot, Régis; ETTAQI, Saïd

    2008-01-01

    International audience; A grade 25 cobalt-based superalloy in the form of a sheet 5 mm in thickness and a steel substrate of type X38CrMoV5 are joined by explosion cladding. The macrostructure and microstructure of the interface and of the co-based superalloy layers are studied. The interface presents the form of wavelets with a period of 1000 µm and an amplitude of 250 µm. The superalloy grains are deformed during the cladding process with several slip systems appearing. Near to the interfac...

  1. Real-space renormalization group study of the Hubbard model on a non-bipartite lattice

    Directory of Open Access Journals (Sweden)

    R. D. Levine

    2002-01-01

    Full Text Available Abstract: We present the real-space block renormalization group equations for fermion systems described by a Hubbard Hamiltonian on a triangular lattice with hexagonal blocks. The conditions that keep the equations from proliferation of the couplings are derived. Computational results are presented including the occurrence of a first-order metal-insulator transition at the critical value of U/t ≈ 12.5.

  2. Lattice dislocation in Si nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Omar, M.S., E-mail: dr_m_s_omar@yahoo.co [Department of Physics, College of Science, University of Salahaddin, Arbil, Iraqi Kurdistan (Iraq); Taha, H.T. [Department of Physics, College of Science, University of Salahaddin, Arbil, Iraqi Kurdistan (Iraq)

    2009-12-15

    Modified formulas were used to calculate lattice thermal expansion, specific heat and Bulk modulus for Si nanowires with diameters of 115, 56, 37 and 22 nm. From these values and Gruneisen parameter taken from reference, mean lattice volumes were found to be as 20.03 A{sup 3} for the bulk and 23.63, 29.91, 34.69 and 40.46 A{sup 3} for Si nanowire diameters mentioned above, respectively. Their mean bonding length was calculated to be as 0.235 nm for the bulk and 0.248, 0.269, 0.282 and 0.297 nm for the nanowires diameter mentioned above, respectively. By dividing the nanowires diameter on the mean bonding length, number of layers per each nanowire size was found to be as 230, 104, 65 and 37 for the diameters mentioned above, respectively. Lattice dislocations in 22 nm diameter wire were found to be from 0.00324 nm for the 1st central lattice to 0.2579 nm for the last surface lattice. Such dislocation was smaller for larger wire diameters. Dislocation concentration found to change in Si nanowires according to the proportionalities of surface thickness to nanowire radius ratios.

  3. Hamiltonian tomography of photonic lattices

    Science.gov (United States)

    Ma, Ruichao; Owens, Clai; LaChapelle, Aman; Schuster, David I.; Simon, Jonathan

    2017-06-01

    In this paper we introduce an approach to Hamiltonian tomography of noninteracting tight-binding photonic lattices. To begin with, we prove that the matrix element of the low-energy effective Hamiltonian between sites α and β may be obtained directly from Sα β(ω ) , the (suitably normalized) two-port measurement between sites α and β at frequency ω . This general result enables complete characterization of both on-site energies and tunneling matrix elements in arbitrary lattice networks by spectroscopy, and suggests that coupling between lattice sites is a topological property of the two-port spectrum. We further provide extensions of this technique for measurement of band projectors in finite, disordered systems with good band flatness ratios, and apply the tool to direct real-space measurement of the Chern number. Our approach demonstrates the extraordinary potential of microwave quantum circuits for exploration of exotic synthetic materials, providing a clear path to characterization and control of single-particle properties of Jaynes-Cummings-Hubbard lattices. More broadly, we provide a robust, unified method of spectroscopic characterization of linear networks from photonic crystals to microwave lattices and everything in between.

  4. Hydrodynamic behaviour of Lattice Boltzmann and Lattice BGK models

    CERN Document Server

    Behrend, O; Warren, P

    1993-01-01

    Abstract: We present a numerical analysis of the validity of classical and generalized hydrodynamics for Lattice Boltzmann Equation (LBE) and Lattice BGK methods in two and three dimensions, as a function of the collision parameters of these models. Our analysis is based on the wave-number dependence of the evolution operator. Good ranges of validity are found for BGK models as long as the relaxation time is chosen smaller than or equal to unity. The additional freedom in the choice of collision parameters for LBE models does not seem to give significant improvement.

  5. Effect of residual elements on high performance nickel base superalloys for gas turbines and strategies for manufacture

    Indian Academy of Sciences (India)

    O P Sinha; M Chatterjee; V V R S Sarma; S N Jha

    2005-07-01

    The need for better gas turbine operating efficiency and reliability has resulted in tightening of specification and acceptance standards. It has been realized that some elements even at trace level, can have disastrous effect on high temperature properties. The present paper highlights the adverse effect of tramp elements and strategies that should be adopted to produce high purity superalloys.

  6. Microstress evolution during in situ loading of a superalloy containing high volume fraction of {gamma}{sup '} phase

    Energy Technology Data Exchange (ETDEWEB)

    Ma, S.; Rangaswamy, P.; Majumdar, B.S

    2003-03-03

    Pulsed neutron diffraction under in situ mechanical loading was used to monitor microstrain evolution in individual phases of a polycrystalline {gamma}/{gamma}{sup '} superalloy, CM 247 LC. The load partitioning and yielding of differently oriented grains and phases were evaluated. The critical resolved shear stresses of individual phases were obtained and are compared with dislocation models.

  7. Hot corrosion resistance of high-velocity oxyfuel sprayed coatings on a nickel-base superalloy in molten salt environment

    Science.gov (United States)

    Sidhu, T. S.; Prakash, S.; Agrawal, R. D.

    2006-09-01

    No alloy is immune to hot corrosion attack indefinitely. Coatings can extend the lives of substrate materials used at higher temperatures in corrosive environments by forming protective oxides layers that are reasonably effective for long-term applications. This article is concerned with studying the performance of high-velocity oxyfuel (HVOF) sprayed NiCrBSi, Cr3C2-NiCr, Ni-20Cr, and Stellite-6 coatings on a nickel-base superalloy at 900 °C in the molten salt (Na2SO4-60% V2O5) environment under cyclic oxidation conditions. The thermogravimetric technique was used to establish kinetics of corrosion. Optical microscope, x-ray diffraction, scanning electron microscopy/electron dispersive analysis by x-ray (SEM/EDAX), and electron probe microanalysis (EPMA) techniques were used to characterize the as-sprayed coatings and corrosion products. The bare superalloy suffered somewhat accelerated corrosion in the given environmental conditions. whereas hot corrosion resistance of all the coated superalloys was found to be better. Among the coating studied, Ni-20Cr coated superalloy imparted maximum hot corrosion resistance, whereas Stellite-6 coated indicated minimum resistance. The hot corrosion resistance of all the coatings may be attributed to the formation of oxides and spinels of nickel, chromium, or cobalt.

  8. Modeling Long-term Creep Performance for Welded Nickel-base Superalloy Structures for Power Generation Systems

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Chen [GE Global Research, NIskayuna, NY (United States); Gupta, Vipul [GE Global Research, NIskayuna, NY (United States); Huang, Shenyan [GE Global Research, NIskayuna, NY (United States); Soare, Monica [GE Global Research, NIskayuna, NY (United States); Zhao, Pengyang [GE Global Research, NIskayuna, NY (United States); Wang, Yunzhi [GE Global Research, NIskayuna, NY (United States)

    2017-02-28

    The goal of this project is to model long-term creep performance for nickel-base superalloy weldments in high temperature power generation systems. The project uses physics-based modeling methodologies and algorithms for predicting alloy properties in heterogeneous material structures. The modeling methodology will be demonstrated on a gas turbine combustor liner weldment of Haynes 282 precipitate-strengthened nickel-base superalloy. The major developments are: (1) microstructure-property relationships under creep conditions and microstructure characterization (2) modeling inhomogeneous microstructure in superalloy weld (3) modeling mesoscale plastic deformation in superalloy weld and (4) a constitutive creep model that accounts for weld and base metal microstructure and their long term evolution. The developed modeling technology is aimed to provide a more efficient and accurate assessment of a material’s long-term performance compared with current testing and extrapolation methods. This modeling technology will also accelerate development and qualification of new materials in advanced power generation systems. This document is a final technical report for the project, covering efforts conducted from October 2014 to December 2016.

  9. Nuclear Reactions from Lattice QCD

    CERN Document Server

    Briceño, Raúl A; Luu, Thomas C

    2014-01-01

    One of the overarching goals of nuclear physics is to rigorously compute properties of hadronic systems directly from the fundamental theory of strong interactions, Quantum Chromodynamics (QCD). In particular, the hope is to perform reliable calculations of nuclear reactions which will impact our understanding of environments that occur during big bang nucleosynthesis, the evolution of stars and supernovae, and within nuclear reactors and high energy/density facilities. Such calculations, being truly ab initio, would include all two-nucleon and three- nucleon (and higher) interactions in a consistent manner. Currently, lattice QCD provides the only reliable option for performing calculations of some of the low- energy hadronic observables. With the aim of bridging the gap between lattice QCD and nuclear many-body physics, the Institute for Nuclear Theory held a workshop on Nuclear Reactions from Lattice QCD on March 2013. In this review article, we report on the topics discussed in this workshop and the path ...

  10. Quantum Gravity on the Lattice

    CERN Document Server

    Hamber, Herbert W

    2009-01-01

    I review the lattice approach to quantum gravity, and how it relates to the non-trivial ultraviolet fixed point scenario of the continuum theory. After a brief introduction covering the general problem of ultraviolet divergences in gravity and other non-renormalizable theories, I cover the general methods and goals of the lattice approach. An underlying theme is an attempt at establishing connections between the continuum renormalization group results, which are mainly based on diagrammatic perturbation theory, and the recent lattice results, which should apply to the strong gravity regime and are inherently non-perturbative. A second theme in this review is the ever-present natural correspondence between infrared methods of strongly coupled non-abelian gauge theories on the one hand, and the low energy approach to quantum gravity based on the renormalization group and universality of critical behavior on the other. Towards the end of the review I discuss possible observational consequences of path integral q...

  11. Algebraic Lattices in QFT Renormalization

    Science.gov (United States)

    Borinsky, Michael

    2016-07-01

    The structure of overlapping subdivergences, which appear in the perturbative expansions of quantum field theory, is analyzed using algebraic lattice theory. It is shown that for specific QFTs the sets of subdivergences of Feynman diagrams form algebraic lattices. This class of QFTs includes the standard model. In kinematic renormalization schemes, in which tadpole diagrams vanish, these lattices are semimodular. This implies that the Hopf algebra of Feynman diagrams is graded by the coradical degree or equivalently that every maximal forest has the same length in the scope of BPHZ renormalization. As an application of this framework, a formula for the counter terms in zero-dimensional QFT is given together with some examples of the enumeration of primitive or skeleton diagrams.

  12. Lattice Structures For Aerospace Applications

    Science.gov (United States)

    Del Olmo, E.; Grande, E.; Samartin, C. R.; Bezdenejnykh, M.; Torres, J.; Blanco, N.; Frovel, M.; Canas, J.

    2012-07-01

    The way of mass reduction improving performances in the aerospace structures is a constant and relevant challenge in the space business. The designs, materials and manufacturing processes are permanently in evolution to explore and get mass optimization solutions at low cost. In the framework of ICARO project, EADS CASA ESPACIO (ECE) has designed, manufactured and tested a technology demonstrator which shows that lattice type of grid structures is a promising weight saving solution for replacing some traditional metallic and composite structures for space applications. A virtual testing methodology was used in order to support the design of a high modulus CFRP cylindrical lattice technology demonstrator. The manufacturing process, based on composite Automatic Fiber Placement (AFP) technology developed by ECE, allows obtaining high quality low weight lattice structures potentially applicable to a wide range of aerospace structures. Launcher payload adaptors, satellite platforms, antenna towers or instrument supports are some promising candidates.

  13. Kaon fluctuations from lattice QCD

    CERN Document Server

    Noronha-Hostler, Jacquelyn; Gunther, Jana; Parotto, Paolo; Pasztor, Attila; Vazquez, Israel Portillo; Ratti, Claudia

    2016-01-01

    We show that it is possible to isolate a set of kaon fluctuations in lattice QCD. By means of the Hadron Resonance Gas (HRG) model, we calculate the actual kaon second-to-first fluctuation ratio, which receives contribution from primordial kaons and resonance decays, and show that it is very close to the one obtained for primordial kaons in the Boltzmann approximation. The latter only involves the strangeness and electric charge chemical potentials, which are functions of $T$ and $\\mu_B$ due to the experimental constraint on strangeness and electric charge, and can therefore be calculated on the lattice. This provides an unambiguous method to extract the kaon freeze-out temperature, by comparing the lattice results to the experimental values for the corresponding fluctuations.

  14. Hadron Structure on the Lattice

    Science.gov (United States)

    Can, K. U.; Kusno, A.; Mastropas, E. V.; Zanotti, J. M.

    The aim of these lectures will be to provide an introduction to some of the concepts needed to study the structure of hadrons on the lattice. Topics covered include the electromagnetic form factors of the nucleon and pion, the nucleon's axial charge and moments of parton and generalised parton distribution functions. These are placed in a phenomenological context by describing how they can lead to insights into the distribution of charge, spin and momentum amongst a hadron's partonic constituents. We discuss the techniques required for extracting the relevant matrix elements from lattice simulations and draw attention to potential sources of systematic error. Examples of recent lattice results are presented and are compared with results from both experiment and theoretical models.

  15. Flavor Physics and Lattice QCD

    CERN Document Server

    Bouchard, C M

    2013-01-01

    Our ability to resolve new physics effects is, largely, limited by the precision with which we calculate. The calculation of observables in the Standard (or a new physics) Model requires knowledge of associated hadronic contributions. The precision of such calculations, and therefore our ability to leverage experiment, is typically limited by hadronic uncertainties. The only first-principles method for calculating the nonperturbative, hadronic contributions is lattice QCD. Modern lattice calculations have controlled errors, are systematically improvable, and in some cases, are pushing the sub-percent level of precision. I outline the role played by, highlight state of the art efforts in, and discuss possible future directions of lattice calculations in flavor physics.

  16. Lattice QCD for nuclear physics

    CERN Document Server

    Meyer, Harvey

    2015-01-01

    With ever increasing computational resources and improvements in algorithms, new opportunities are emerging for lattice gauge theory to address key questions in strongly interacting systems, such as nuclear matter. Calculations today use dynamical gauge-field ensembles with degenerate light up/down quarks and the strange quark and it is possible now to consider including charm-quark degrees of freedom in the QCD vacuum. Pion masses and other sources of systematic error, such as finite-volume and discretization effects, are beginning to be quantified systematically. Altogether, an era of precision calculation has begun, and many new observables will be calculated at the new computational facilities.  The aim of this set of lectures is to provide graduate students with a grounding in the application of lattice gauge theory methods to strongly interacting systems, and in particular to nuclear physics.  A wide variety of topics are covered, including continuum field theory, lattice discretizations, hadron spect...

  17. Blocked Urethral Valves

    Science.gov (United States)

    ... Blocked Urethral Valves Health Issues Listen Español Text Size Email Print Share Blocked Urethral Valves Page Content Article Body Urine leaves the bladder through a tube called the urethra, which in boys passes through the penis. Rarely, small membranes form across the urethra in ...

  18. Related Drupal Nodes Block

    NARCIS (Netherlands)

    Van der Vegt, Wim

    2010-01-01

    Related Drupal Nodes Block This module exposes a block that uses Latent Semantic Analysis (Lsa) internally to suggest three nodes that are relevant to the node a user is viewing. This module performs three tasks. 1) It periodically indexes a Drupal site and generates a Lsa Term Document Matrix. Inde

  19. Types of Heart Block

    Science.gov (United States)

    ... P wave as it normally would. If an electrical signal is blocked before it reaches the ventricles, they won't contract and pump blood to the lungs and the rest of the body. Second-degree heart block is divided into two ...

  20. Related Drupal Nodes Block

    NARCIS (Netherlands)

    Van der Vegt, Wim

    2010-01-01

    Related Drupal Nodes Block This module exposes a block that uses Latent Semantic Analysis (Lsa) internally to suggest three nodes that are relevant to the node a user is viewing. This module performs three tasks. 1) It periodically indexes a Drupal site and generates a Lsa Term Document Matrix. Inde

  1. Nucleon structure from lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Dinter, Simon

    2012-11-13

    In this thesis we compute within lattice QCD observables related to the structure of the nucleon. One part of this thesis is concerned with moments of parton distribution functions (PDFs). Those moments are essential elements for the understanding of nucleon structure and can be extracted from a global analysis of deep inelastic scattering experiments. On the theoretical side they can be computed non-perturbatively by means of lattice QCD. However, since the time lattice calculations of moments of PDFs are available, there is a tension between these lattice calculations and the results from a global analysis of experimental data. We examine whether systematic effects are responsible for this tension, and study particularly intensively the effects of excited states by a dedicated high precision computation. Moreover, we carry out a first computation with four dynamical flavors. Another aspect of this thesis is a feasibility study of a lattice QCD computation of the scalar quark content of the nucleon, which is an important element in the cross-section of a heavy particle with the nucleon mediated by a scalar particle (e.g. Higgs particle) and can therefore have an impact on Dark Matter searches. Existing lattice QCD calculations of this quantity usually have a large error and thus a low significance for phenomenological applications. We use a variance-reduction technique for quark-disconnected diagrams to obtain a precise result. Furthermore, we introduce a new stochastic method for the calculation of connected 3-point correlation functions, which are needed to compute nucleon structure observables, as an alternative to the usual sequential propagator method. In an explorative study we check whether this new method is competitive to the standard one. We use Wilson twisted mass fermions at maximal twist in all our calculations, such that all observables considered here have only O(a{sup 2}) discretization effects.

  2. The Block Neighborhood

    CERN Document Server

    Arrighi, Pablo

    2010-01-01

    We define the block neighborhood of a reversible CA, which is related both to its decomposition into a product of block permutations and to quantum computing. We give a purely combinatorial characterization of the block neighborhood, which helps in two ways. First, it makes the computation of the block neighborhood of a given CA relatively easy. Second, it allows us to derive upper bounds on the block neighborhood: for a single CA as function of the classical and inverse neighborhoods, and for the composition of several CAs. One consequence of that is a characterization of a class of "elementary" CAs that cannot be written as the composition of two simpler parts whose neighborhoods and inverse neighborhoods would be reduced by one half.

  3. Lattice studies of quark spectra and supersymmetric quantum mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Schierenberg, Sebastian

    2012-06-24

    In the first part of this work, we study quark spectra at either non-zero temperature or chemical potential. In the first case, we find a possible explanation for the Anderson localization that is observed in the spectrum. We introduce a random matrix model that has the same localization and shares other important properties of the QCD Dirac operator, too. In the case of a non-vanishing chemical potential, we show that the eigenvalue spacing distributions of the Dirac operator are described by simple random matrix models. In the second part of this work, we study supersymmetry on the lattice. We summarize our progress with the blocking approach and show possible problems. Furthermore, we construct a lattice action which is improved with respect to supersymmetry and study this action numerically.

  4. Nuclear Physics from Lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    William Detmold, Silas Beane, Konstantinos Orginos, Martin Savage

    2011-01-01

    We review recent progress toward establishing lattice Quantum Chromodynamics as a predictive calculational framework for nuclear physics. A survey of the current techniques that are used to extract low-energy hadronic scattering amplitudes and interactions is followed by a review of recent two-body and few-body calculations by the NPLQCD collaboration and others. An outline of the nuclear physics that is expected to be accomplished with Lattice QCD in the next decade, along with estimates of the required computational resources, is presented.

  5. Chiral Fermions on the Lattice

    CERN Document Server

    Bietenholz, Wolfgang

    2010-01-01

    In the last century the non-perturbative regularization of chiral fermions was a long-standing problem. We review how this problem was finally overcome by the formulation of a modified but exact form of chiral symmetry on the lattice. This also provides a sound definition of the topological charge of lattice gauge configurations. We illustrate a variety of applications to QCD in the p-, the epsilon- and the delta-regime, where simulation results can now be related to Random Matrix Theory and Chiral Perturbation Theory. The latter contains Low Energy Constants as free parameters, and we comment on their evaluation from first principles of QCD.

  6. Lattices, graphs, and Conway mutation

    CERN Document Server

    Greene, Joshua Evan

    2011-01-01

    The d-invariant of an integral, positive definite lattice L records the minimal norm of a characteristic covector in each equivalence class mod 2L. We prove that the 2-isomorphism type of a connected graph is determined by the d-invariant of its lattice of integral cuts (or flows). As an application, we prove that a reduced, alternating link diagram is determined up to mutation by the Heegaard Floer homology of the link's branched double-cover. Thus, alternating links with homeomorphic branched double-covers are mutants.

  7. Graphene on graphene antidot lattices

    DEFF Research Database (Denmark)

    Gregersen, Søren Schou; Pedersen, Jesper Goor; Power, Stephen

    2015-01-01

    Graphene bilayer systems are known to exhibit a band gap when the layer symmetry is broken by applying a perpendicular electric field. The resulting band structure resembles that of a conventional semiconductor with a parabolic dispersion. Here, we introduce a bilayer graphene heterostructure......, where single-layer graphene is placed on top of another layer of graphene with a regular lattice of antidots. We dub this class of graphene systems GOAL: graphene on graphene antidot lattice. By varying the structure geometry, band-structure engineering can be performed to obtain linearly dispersing...

  8. Unconventional superconductivity in honeycomb lattice

    Directory of Open Access Journals (Sweden)

    P Sahebsara

    2013-03-01

    Full Text Available   ‎ The possibility of symmetrical s-wave superconductivity in the honeycomb lattice is studied within a strongly correlated regime, using the Hubbard model. The superconducting order parameter is defined by introducing the Green function, which is obtained by calculating the density of the electrons ‎ . In this study showed that the superconducting order parameter appears in doping interval between 0 and 0.5, and x=0.25 is the optimum doping for the s-wave superconductivity in honeycomb lattice.

  9. Grain Boundary Engineering of a Low Stacking Fault Energy Ni-based Superalloy

    Science.gov (United States)

    McCarley, Joshua; Helmink, Randolph; Goetz, Robert; Tin, Sammy

    2017-04-01

    The effects of thermo-mechanical processing parameters on the resulting microstructure of an experimental Nickel-based superalloy containing 24 wt pct Co were investigated. Hot compression tests were performed at temperatures ranging from 1293 K to 1373 K (1020 to 1100 °C) and strain rates ranging from 0.0005 to 0.1/s. The mechanically deformed samples were also subject to annealing treatments at sub-solvus 1388 K (1115 °C) and super-solvus 1413 K (1140 °C) temperatures. This investigation sought to quantify and subsequently understand the behavior and evolution of both the grain boundary structure and length fraction of Σ3 twin boundaries in the low stacking fault energy superalloy. Over the range of deformation parameters investigated, the corresponding deformation mechanism map revealed that dynamic recrystallization or dynamic recovery was dominant. These conditions largely promoted post-deformation grain refinement and the formation of annealing twins following annealing. Samples deformed at strain rates of 0.0005 and 0.001/s at 1333 K and 1373 K (1060 °C and 1100 °C) exhibited extensive grain boundary sliding/rotation associated with superplastic flow. Upon annealing, deformation conditions that resulted predominately in superplastic flow were found to provide negligible enhancement of twin boundaries and produced little to no post-deformation grain refinement.

  10. High-temperature γ (FCC/γ′ (L12 Co-Al-W based superalloys

    Directory of Open Access Journals (Sweden)

    Knop Matthias

    2014-01-01

    Full Text Available Interim results from the development of a polycrystalline Co-Al-W based superalloy are presented. Cr has been added to provide oxidation resistance and Ni has then been added to widen and stabilise the γ′ phase field. The alloy presented has a solvus of 1010 °C and a density of 8.7 g cm−3. The room temperature flow stress is over 1000 MPa and this reduces dramatically above 800 °C. The flow stress anomaly is observed. A microstructure with both ∼ 50 nm γ′ produced on cooling and larger 100–200 nm γ′ can be obtained. Isothermal oxidation at 800 °C in air for 200 h gave a mass gain of 0.96 mg cm−2. After hot deformation in the 650–850 °C temperature range, both anti phase boundaries (APBs and stacking faults could be observed. An APB energy of 71 mJ m−2 was measured, which is comparable to that found in commercial nickel superalloys.

  11. Processing maps for Fe–24Ni–11Cr–3Ti–1Mo superalloy

    Indian Academy of Sciences (India)

    Cai Dayong; Zhang Chunling; Tang Zhiguo; Dong Haifeng; Wang Peng

    2011-06-01

    Hot deformation characteristics of a Fe-base superalloy were studied at various temperatures from 1000–1200°C under strain rates from 0.001–1 s-1 using hot compression tests. Processing maps for hot working are developed on the basis of the variations of efficiency of power dissipation with temperature and strain rate and interpreted by a dynamic materials model. Hot deformation equation was given to characterize the dependence of peak stress on deformation temperature and strain rate. Hot deformation apparent activation energy of the Fe–24Ni–11Cr–1Mo–3Ti superalloy was determined to be about 499 kJ/mol. The processing maps obtained in a strain range of 0.1–0.7 were essentially similar, indicating that strain has no significant influence on it. The processing maps exhibited a clear domain with a maximum of about 40–48% at about 1150°C and 0.001 s-1.

  12. Grain Boundary Engineering of a Low Stacking Fault Energy Ni-based Superalloy

    Science.gov (United States)

    McCarley, Joshua; Helmink, Randolph; Goetz, Robert; Tin, Sammy

    2017-02-01

    The effects of thermo-mechanical processing parameters on the resulting microstructure of an experimental Nickel-based superalloy containing 24 wt pct Co were investigated. Hot compression tests were performed at temperatures ranging from 1293 K to 1373 K (1020 to 1100 °C) and strain rates ranging from 0.0005 to 0.1/s. The mechanically deformed samples were also subject to annealing treatments at sub-solvus 1388 K (1115 °C) and super-solvus 1413 K (1140 °C) temperatures. This investigation sought to quantify and subsequently understand the behavior and evolution of both the grain boundary structure and length fraction of Σ3 twin boundaries in the low stacking fault energy superalloy. Over the range of deformation parameters investigated, the corresponding deformation mechanism map revealed that dynamic recrystallization or dynamic recovery was dominant. These conditions largely promoted post-deformation grain refinement and the formation of annealing twins following annealing. Samples deformed at strain rates of 0.0005 and 0.001/s at 1333 K and 1373 K (1060 °C and 1100 °C) exhibited extensive grain boundary sliding/rotation associated with superplastic flow. Upon annealing, deformation conditions that resulted predominately in superplastic flow were found to provide negligible enhancement of twin boundaries and produced little to no post-deformation grain refinement.

  13. Structure property characterization of rheocast and VADER processed IN-100 superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, J.J.A.

    1985-01-01

    Two recent solidification processes were applied in production of IN-100 nickel-base superalloy: rheocasting and Vacuum ARc Double Electrode Remelting (VADER). A high vacuum furnace for rheocasting superalloys was built and was used to rheocast ingots under different processing conditions. Processing variables evaluated include stirring speed, isothermal stirring time and volume fraction solid during isothermal stirring. VADER processed IN-100 was purchased from Special Metals Corp. As-cast ingots were subjected to various thermal treatments including hot isostatic pressing and heat treatment. As-cast and thermally treated materials were characterized using optical and scanning electron microscopy and microprobe analysis. Both rheocasting and VADER-processed materials yield fine and equiaxed spherical structures, where the extent of macrosegregation is lesser in comparison to conventionally produced ingot material. In rheocasting, the formation of nondendritic structures is discussed further on the basis of the model of dendrite arm fragmentation. At a constant cooling rate, the grain size and macrosegregation of the as-cast ingot is reduced by increasing the stirring speed, isothermal stirring time or the volume fraction solid during solidification, however, stirring speed has a more pronounced effect on grain refinement and macro-scale chemical homogeneity than the other two variables. The degree of the microsegregation decreases with increasing volume fraction solid and/or isothermal stirring time.

  14. Prediction of recrystallisation in single crystal nickel-based superalloys during investment casting

    Directory of Open Access Journals (Sweden)

    Panwisawas Chinnapat

    2014-01-01

    Full Text Available Production of gas turbines for jet propulsion and power generation requires the manufacture of turbine blades from single crystal nickel-based superalloys, most typically using investment casting. During the necessary subsequent solution heat treatment, the formation of recrystallised grains can occur. The introduction of grain boundaries into a single crystal component is potentially detrimental to performance, and therefore manufacturing processes and/or component geometries should be designed to prevent their occurrence. If the boundaries have very low strength, they can degrade the creep and fatigue properties. The root cause for recrystallisation is microscale plasticity caused by differential thermal contraction of metal, mould and core; when the plastic deformation is sufficiently large, recrystallisation takes place. In this work, numerical and thermo-mechanical modelling is carried out, with the aim of establishing computational methods by which recrystallisation during the heat treatment of single crystal nickel-based superalloys can be predicted and prevented prior to their occurrence. Elasto-plastic law is used to predict the plastic strain necessary for recrystallisation. The modelling result shows that recrystallisation is most likely to occur following 1.5–2.5% plastic strain applied at temperatures between 1000 ∘C and 1300 ∘C; this is validated with tensile tests at these elevated temperatures. This emphasises that high temperature deformation is more damaging than low temperature deformation.

  15. High Temperature Degradation of Powder-processed Ni-based Superalloy

    Directory of Open Access Journals (Sweden)

    Natália Luptáková

    2015-05-01

    Full Text Available The aim of present work is to study the high temperature degradation of the powder-processed polycrystalline superalloy Ni-15Cr-18Co-4Al-3.5Ti-5Mo. This superalloy has been applied as material for grips of a creep machine. The material was exposed at 1100 °C for about 10 days at 10 MPa stress. During the creep test occurred unacceptable creep deformation of grips as well as severe surface oxidation with scales peeling off. Three types of the microstructure were observed in the studied alloy: (i unexposed state; (ii heat treated (annealing - 10 min/1200 °C and (iii after using as a part of the equipment of the creep machine during the creep test. It is shown that the microstructure degradation resulting from the revealed γ´ phase fcc Ni3(Al,Ti particles preferentially created at the grain boundaries of the samples after performing creep tests affects mechanical properties of the alloy and represents a significant contribution to all degradation processes affecting performance and service life of the creep machine grips. Based on investigation and obtained results, the given material is not recommended to be used for grips of creep machine at temperatures above 1000 °C.

  16. Enhancing the Oxidation Performance of Wrought Ni-Base Superalloy by Minor Additions of Active Elements

    Science.gov (United States)

    Tawancy, H. M.

    2016-12-01

    We show that the oxidation performance of Cr2O3-forming superalloy based upon the Ni-Cr-W system is significantly improved by the presence of minor concentrations of La, Si and Mn, which outweigh the detrimental effect of high W concentration in the alloy. Although Cr2O3 is known to transform into volatile CrO3 at temperatures ≥950 °C, the respective protection is extended to temperatures reaching 1150 °C, which has also been correlated with the beneficial effects of La, Si and Mn. During high-temperature oxidation, an inner protective La- and Si-modified layer of α-Cr2O3 in contact with the superalloy substrate is developed and shielded by an outermost layer of MnCr2O4. The distribution of La and Si in the inner oxide layer has been characterized down to the scale of transmission electron microscopy, and the possible mechanisms underlying their beneficial effects are elucidated.

  17. Fatigue Resistance of the Grain Size Transition Zone in a Dual Microstructure Superalloy Disk

    Science.gov (United States)

    Gabb, T. P.; Kantzos, P. T.; Telesman, J.; Gayda, J.; Sudbrack, C. K.; Palsa, B. S.

    2010-01-01

    Mechanical property requirements vary with location in nickel-based superalloy disks. To maximize the associated mechanical properties, heat treatment methods have been developed for producing tailored microstructures. In this study, a specialized heat treatment method was applied to produce varying grain microstructures from the bore to the rim portions of a powder metallurgy processed nickel-based superalloy disk. The bore of the contoured disk consisted of fine grains to maximize strength and fatigue resistance at lower temperatures. The rim microstructure of the disk consisted of coarse grains for maximum resistance to creep and dwell crack growth at high temperatures up to 704 C. However, the fatigue resistance of the grain size transition zone was unclear, and needed to be evaluated. This zone was located as a band in the disk web between the bore and rim. Specimens were extracted parallel and transverse to the transition zone, and multiple fatigue tests were performed at 427 and 704 C. Mean fatigue lives were lower at 427 C than for 704 C. Specimen failures often initiated at relatively large grains, which failed on crystallographic facets. Grain size distributions were characterized in the specimens, and related to the grains initiating failures as well as location within the transition zone. Fatigue life decreased with increasing maximum grain size. Correspondingly, mean fatigue resistance of the transition zone was slightly higher than that of the rim, but lower than that of the bore. The scatter in limited tests of replicates was comparable for all transition zone locations examined.

  18. Degradation of nonmodified and rhodium modified aluminide coating deposited on CMSX 4 superalloy.

    Science.gov (United States)

    Zagula-Yavorska, Maryana; Wierzbińska, Małgorzata; Gancarczyk, Kamil; Sieniawski, Jan

    2016-07-01

    The Ni-base superalloy CMSX 4 used in the turbine blades of aircraft engines was coated with rhodium layer (0.5-μm thick). Next coated CMSX 4 superalloy was aluminized by the CVD method. The rhodium modified aluminide coating and nonmodified aluminide coating were oxidized at 1100°C at the air atmosphere. The rhodium modified aluminide coating showed about twice better oxidation resistance than the nonmodified one. The spallation equal 62% of the total area was observed on the surface of the nonmodified coating whereas only 36% spallation area was observed on the surface of the rhodium modified aluminide coating after the oxidation test. The oxide layer formed on the surface of the nonmodified coating was composed of nonprotective (Ni,Cr)Al2 O4 and (Ni,Cr)O phases. Aluminium in the coating reacts with oxygen, forming a protective α-Al2 O3 oxide on the surface of the rhodium modified aluminide coating. When the oxide cracks and spalls due to oxidation, additional aluminium from the coating diffuses to the surface to form the oxide. The presence of protective Al2 O3 oxide on the surface of the rhodium modified aluminide coating slows coating degradation. Therefore, rhodium modified aluminide coating has better oxidation resistance than the nonmodified one.

  19. Mapping single-crystal dendritic microstructure and defects in nickel-base superalloys with synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Husseini, Naji S. [Applied Physics Program, University of Michigan, Ann Arbor, MI 48109 (United States)], E-mail: najihuss@umich.edu; Kumah, Divine P. [Applied Physics Program, University of Michigan, Ann Arbor, MI 48109 (United States); Yi, Jian Z.; Torbet, Christopher J. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Arms, Dohn A.; Dufresne, Eric M. [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Pollock, Tresa M.; Wayne Jones, J. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Clarke, Roy [Applied Physics Program, University of Michigan, Ann Arbor, MI 48109 (United States)

    2008-10-15

    Solidification of single-crystal nickel-base superalloys introduces large-scale segregation of constituent elements and defects such as dislocations and mosaicity. By exploiting the energy tunability and interference capabilities of high-brilliance X-ray radiation, key structural features of the dendritic single crystals were mapped over large areas. Interference and diffraction of synchrotron X-rays revealed significant misorientations between individual dendrites in the as-solidified state. For the first time this mosaic structure was quantified for an array of dendrites and correlated with the density of 'grown-in' dislocations whose density ranged from 10{sup 7} to 10{sup 8} cm{sup -2}. Absorption contrast permitted simultaneous mapping of the distribution of refractory metal additives (e.g. rhenium and tungsten), which segregated preferentially to the dendrite cores with a linear composition gradient toward the interdendritic regions. The results demonstrate that synchrotron X-ray imaging is promising for in situ studies of single-crystal structure and defects in nickel-base superalloys.

  20. Influence of Ta content on hot corrosion behaviour of a directionally solidified nickel base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Han, F.F. [Superalloy Division, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Chang, J.X., E-mail: jxchang11s@imr.ac.cn [Superalloy Division, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Li, H.; Lou, L.H. [Superalloy Division, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Zhang, J. [Superalloy Division, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2015-01-15

    Highlights: • Three nickel-base superalloys containing different Ta content were subjected to Na{sub 2}SO{sub 4}-induced hot corrosion. • Ta improved the hot corrosion resistance. • Ta decreased the diffusion rate of alloying elements. • Ta promoted the formation of (Cr, Ti)TaO{sub 4} layer. - Abstract: Hot corrosion behaviour of a directionally solidified nickel base superalloy with different tantalum (Ta) addition in fused sodium sulphate (Na{sub 2}SO{sub 4}) under an oxidizing atmosphere at 900 °C has been studied. It was shown that the hot corrosion resistance was improved by increasing of Ta content. The hot corrosion kinetics of the alloy with lower Ta content deviated from parabolic law after 60 h corrosion test, whereas the corrosion kinetics of the alloy with high Ta content followed the parabolic law before 60 h and with less mass change afterwards. A detailed microstructure study using scanning electron microscopy (SEM) equipped with an energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffraction (XRD) was performed to investigate the corrosion products and mechanisms. The beneficial effect of Ta was found to be resulted from a Ta-enriched (Cr, Ti)TaO{sub 4} layer inside the corrosion scale, which led to the retarding of the element diffusion so as to decrease the hot corrosion kinetics.

  1. An experimental study on quasi-CW fibre laser drilling of nickel superalloy

    Science.gov (United States)

    Marimuthu, S.; Antar, M.; Dunleavey, J.; Chantzis, D.; Darlington, W.; Hayward, P.

    2017-09-01

    Laser drilling of metals and alloys is extensively used in modern manufacturing industries to produce holes of various size and shape. Currently, most laser drilling of aerospace nickel superalloys is performed using Nd:YAG laser. Over the years, many attempts were made to increase the productivity of Nd:YAG lasers drilling process, but with little success. This paper investigates the fundamental aspects of millisecond-pulsed-Quasi-CW-fibre laser drilling of aerospace nickel superalloy. The main investigation concentrates on understanding the Quasi-CW-fibre laser parameters on trepanning laser drilled hole quality and speed. The principal findings are based on controlling the recast layer, oxide layer, hole surface characteristic and fatigue performance of the laser drilled samples. The results showed that the high average power of the quasi-CW-fibre lasers can be effectively used to achieve increased trepanning drilling speed without undermining the drilling quality, which is not feasible with a free-space Nd:YAG laser. Also, low peak power and high frequency (of quasi-CW-fibre laser) can be effectively used to produce better laser drilled holes than the high peak power and low frequency, which is common with the traditional millisecond Nd:YAG drilling processes. Recast layer thickness of around 30 μm can be achieved with a trepanning speed of up to 500 mm/min with single orbit Quasi-CW fibre laser drilling of 0.75 mm hole over 5 mm thick material.

  2. Technology of laser repair welding of nickel superalloy inner flaps of jet engine

    Directory of Open Access Journals (Sweden)

    A. Klimpel

    2011-07-01

    Full Text Available Purpose: of this paper: work out laser welding repair technology of cracked MIG 29 jet engine inner flaps made of cast nickel superalloy ŻS-3DK (ЖС-3ДК, Russian designation.Design/methodology/approach: The study were based on the analysis of laser HPDL powder INCONEL 625 welding of nickel superalloy using wide range of welding parameters to provide highest quality repair welds.Findings: Study of automatic welding technologies GTA, PTA and laser HPDL has shown that just laser welding can provide high quality repair welds. In order to establish the properties of welded joints repair cracks in the inner flap HPDL laser, studied the hardness, mechanical properties and erosive wear resistance.Research limitations/implications: It was found that only laser HPDL welding can provide high quality repair welds.Practical implications: The technology can be applied for repair cracked MIG 29 jet engine inner flaps.Originality/value: Repairing cracked MIG 29 jet engine inner flaps.

  3. Microstructural characteristics and mechanical properties of HVOF sprayed NiCrAl coating on superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Mahesh, R.A. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Jayaganthan, R. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India)], E-mail: rjayafmt@iitr.ernet.in; Prakash, S. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

    2009-01-22

    High velocity oxy-fuel (HVOF) process sprayed NiCrAl coatings on superalloys were characterized by various techniques such as optical microscopy, X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive spectroscopic analysis (SEM/EDS) to render an insight into their microstrucural features and assess its suitability for high temperature corrosion resistance applications. The as sprayed coatings were found to be dense with splat like layered morphology. The XRD analysis of the coating showed the presence of Ni (fcc) as a prominent phase with Cr and Al as minor phases. The porosity of the coatings was calculated from its optical micrographs and found to be less than 1.7%. The measured hardness and average bond strength of the coatings were found to be in the range of 278-351 Hv and 59 MPa, respectively. The observed microstructral characteristics, higher bond strength, and hardness of HVOF sprayed NiCrAl coating show that it may act as an effective barrier to provide high temperature protection to the superalloys.

  4. Microstructure Modeling of a Ni-Fe-Based Superalloy During the Rotary Forging Process

    Science.gov (United States)

    Loyda, A.; Hernández-Muñoz, G. M.; Reyes, L. A.; Zambrano-Robledo, P.

    2016-06-01

    The microstructure evolution of Ni-Fe superalloys has a great influence on the mechanical behavior during service conditions. The rotary forging process offers an alternative to conventional bulk forming processes where the parts can be rotary forged with a fraction of the force commonly needed by conventional forging techniques. In this investigation, a numerical modeling of microstructure evolution for design and optimization of the hot forging operations has been used to manufacture a heat-resistant nickel-based superalloy. An Avrami model was implemented into finite element commercial platform DEFORM 3D to evaluate the average grain size and recrystallization during the rotary forging process. The simulations were carried out considering three initial temperatures, 980, 1000, and 1050 °C, to obtain the microstructure behavior after rotary forging. The final average grain size of one case was validated by comparing with results of previous experimental work of disk forging operation. This investigation was aimed to explore the influence of the rotary forging process on microstructure evolution in order to obtain a homogenous and refined grain size in the final component.

  5. Effect of Heat Treatment Process on Microstructure and Fatigue Behavior of a Nickel-Base Superalloy

    Directory of Open Access Journals (Sweden)

    Peng Zhang

    2015-09-01

    Full Text Available The study of fatigue behaviors for nickel-base superalloys is very significant because fatigue damage results in serious consequences. In this paper, two kinds of heat treatment procedures (Pro.I and Pro.II were taken to investigate the effect of heat treatment on microstructures and fatigue behaviors of a nickel-base superalloy. Fatigue behaviors were studied through total strain controlled mode at 650 °C. Manson-Coffin relationship and three-parameter power function were used to predict fatigue life. A good link between the cyclic/fatigue behavior and microscopic studies was established. The cyclic deformation mechanism and fatigue mechanism were discussed. The results show that the fatigue resistance significantly drops with the increase of total strain amplitudes. Manson-Coffin relationship can well predict the fatigue life for total strain amplitude from 0.5% to 0.8%. The fatigue resistance is related with heat treatment procedures. The fatigue resistance performance of Pro.I is better than that of Pro.II. The cyclic stress response behaviors are closely related to the changes of the strain amplitudes. The peak stress of the alloy gradually increases with the increase of total strain amplitudes. The main fracture mechanism is inhomogeneous deformation and the different interactions between dislocations and γ′ precipitates.

  6. Effect of HIP Combined with RHT Process on Creep Damage of DZ125 Superalloy

    Directory of Open Access Journals (Sweden)

    WANG Tian-you

    2017-02-01

    Full Text Available Four different processes of hot isostatic pressing (HIP combined with rejuvenation heat treatments (RHT were adopted to reveal the microstructural evolution of creep damaged DZ125 specimens, finally the mechanical properties were evaluated.The results show that both γ' precipitate degeneration and creep cavities for the creep damaged DZ125 superalloy are found after the pre-endurance damage test.However, the carbided compositions from MC type to M23C6 type or M6C type has not been observed for DZ125.In addition, it is found that the HIP temperature play a dominant role in the cavity healing process for the damaged specimens. The concentrically oriented γ' rafting structure and the incipient melting are observed at 1200℃ and 1250℃ respectively.Meanwhile, it is found that the appropriate HIP schedule adopted can effectively avoid the internal recrystallization for the directionally solidified nickel-based superalloy DZ125. The appropriate HIP schedule combined with RHT process can successfully restore the microstructure induced by creep damage and recover the degraded micro-hardness to the original one, in addition improve the creep rupture life.

  7. Influence of cooling rate on y'morphology in cast Ni – base superalloy

    Directory of Open Access Journals (Sweden)

    J. Belan

    2009-04-01

    Full Text Available The Ni – base superalloys, which are combined an unique physical and mechanical properties, are used in aircraft industry for productionof aero engine most stressed parts, as are turbine blades. From this reason a dendrite arm spacing, carbides size and distribution, morphology,number and value of y'- phase are very important structural characteristics for blade lifetime prediction as well as aero engine its self. In this article are used methods of quantitative metallography (software LUCIA for carbides evaluation, measuring of secondary dendrite arm spacing and coherent testing grid for y' - phase evaluation for evaluation of structural characteristics mentioned above on experimental material – Ni base superalloy ŽS6K. The high temperature effect represented here by heat treatment at 800°C followed with holding time about 10 hours, and cooling rate, here represented by three various cooling mediums as water, air, and oil, on structural characteristics and application of quantitative methods evaluation are presented in this paper.

  8. The cyclic oxidation behavior of the single crystal TMS-82+ superalloy in humidified air

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y. [School of Materials Science and Engineering, Shanghai, Institute of Technology, Shanghai (China); Research Group of Interface Control Engineering, Graduate School of Engineering, Hokkaido University, Sapporo (Japan); Narita, T. [Research Group of Interface Control Engineering, Graduate School of Engineering, Hokkaido University, Sapporo (Japan)

    2009-10-15

    The cyclic oxidation behavior of a single crystal Ni-based superalloy TMS-82+ was studied at 800 and 900 C for 200 h in water vapor (air plus 15% H{sub 2}O). Regardless of the exposure temperature, time-dependence of the growth rate of the scale for the superalloy was fitted by a subparabolic relationship. The oxidation rate was enhanced with increase in exposure temperature, which was evidenced by a higher mass gain and thicker scale. The oxides on the specimen at 800 C consisted of (Ni,Co)O, CrTaO{sub 4}, AlTaO{sub 4}, Cr{sub 2}O{sub 3}, and {theta}-Al{sub 2}O{sub 3}, whereas for the specimen exposed at 900 C, spinels of NiCr{sub 2}O{sub 4} and (Ni,Co)Al{sub 2}O{sub 4} as well as {alpha}-Al{sub 2}O{sub 3} were observed. An innermost dense {alpha}-Al{sub 2}O{sub 3} layer was responsible for a stable growth rate of the scale after the initial rapid oxidation. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  9. Methodology of Ni-base Superalloy Development for VHTR using Design of Experiments and Thermodynamic Calculation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sungwoo; Kim, Dongjin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-03-15

    This work is concerning a methodology of Ni-base superalloy development for a very high temperature gas-cooled reactor(VHTR) using design of experiments(DOE) and thermodynamic calculations. Total 32 sets of the Ni-base superalloys with various chemical compositions were formulated based on a fractional factorial design of DOE, and the thermodynamic stability of topologically close-packed(TCP) phases of those alloys was calculated by using the THERMO-CALC software. From the statistical evaluation of the effect of the chemical composition on the formation of TCP phase up to a temperature of 950 .deg. C, which should be suppressed for prolonged service life when it used as the structural components of VHTR, 16 sets were selected for further calculation of the mechanical properties. Considering the yield and ultimate tensile strengths of the selected alloys estimated by using the JMATPRO software, the optimized chemical composition of the alloys for VHTR application, especially intermediate heat exchanger, was proposed for a succeeding experimental study.

  10. Solution and Aging of MAR-M246 Nickel-Based Superalloy

    Science.gov (United States)

    Baldan, Renato; da Silva, Antonio Augusto Araújo Pinto; Nunes, Carlos Angelo; Couto, Antonio Augusto; Gabriel, Sinara Borborema; Alkmin, Luciano Braga

    2017-02-01

    Solution and aging heat-treatments play a key role for the application of the superalloys. The aim of this work is to evaluate the microstructure of the MAR-M246 nickel-based superalloy solutioned at 1200 and 1250 °C for 330 min and aged at 780, 880 and 980 °C for 5, 20 and 80 h. The γ' solvus, solidus and liquidus temperatures were calculated with the aid of the JMatPro software (Ni database). The as-cast and heat-treated samples were characterized by SEM/EDS and SEM-FEG. The γ' size precipitated in the aged samples was measured and compared with JMatPro simulations. The results have shown that the sample solutioned at 1250 °C for 330 min showed a very homogeneous γ matrix with carbides and cubic γ' precipitates uniformly distributed. The mean γ' size of aged samples at 780 and 880 °C for 5, 20 and 80 h did not present significant differences when compared to the solutioned sample. However, a significant increasing in the γ' particles was observed at 980 °C, evidenced by the large mean size of these particles after 80 h of aging heat-treatment.

  11. Designing Nanoscale Precipitates in Novel Cobalt-based Superalloys to Improve Creep Resistance and Operating Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Dunand, David C. [Northwestern Univ., Evanston, IL (United States); Seidman, David N. [Northwestern Univ., Evanston, IL (United States); Wolverton, Christopher [Northwestern Univ., Evanston, IL (United States); Saal, James E. [Northwestern Univ., Evanston, IL (United States); Bocchini, Peter J. [Northwestern Univ., Evanston, IL (United States); Sauza, Daniel J. [Northwestern Univ., Evanston, IL (United States)

    2014-10-01

    High-temperature structural alloys for aerospace and energy applications have long been dominated by Ni-base superalloys, whose strength and creep resistance can be attributed to microstructures consisting of a large volume fraction of ordered (L12) γ'-precipitates embedded in a disordered’(f.c.c.) γ-matrix. These alloys exhibit excellent mechanical behavior and thermal stability, but after decades of incremental improvement are nearing the theoretical limit of their operating temperatures. Conventional Co-base superalloys are solid-solution or carbide strengthened; although they see industrial use, these alloys are restricted to lower-stress applications because the absence of an ordered intermetallic phase places an upper limit on their mechanical performance. In 2006, a γ+γ' microstructure with ordered precipitates analogous to (L12) Ni3Al was first identified in the Co-Al-W ternary system, allowing, for the first time, the development of Co-base alloys with the potential to meet or even exceed the elevated-temperature performance of their Ni-base counterparts. The potential design space for these alloys is complex: the most advanced Ni-base superalloys may contain as many as 8-10 minor alloying additions, each with a specified purpose such as raising the γ' solvus temperature or improving creep strength. Our work has focused on assessing the effects of alloying additions on microstructure and mechanical behavior of γ'-strengthened Co-base alloys in an effort to lay the foundations for understanding this emerging alloy system. Investigation of the size, morphology, and composition of γ' and other relevant phases is investigated utilizing scanning electron microscopy (SEM) and 3-D picosecond ultraviolet local electrode atom probe tomography (APT). Microhardness, compressive yield stress at ambient and elevated temperatures, and compressive high-temperature creep measurements are employed to

  12. Response to Discussion of "Investigation of Oxide Bifilms in Investment Cast Superalloy IN100 Part I and II"

    Science.gov (United States)

    Kaplan, M. A.; Fuchs, G. E.

    2017-10-01

    In his most recent letter (Campbell in Met Trans A, 2017), Professor Campbell provides additional comments on Kaplan and Fuchs papers "Oxides Bifilms in Superalloy: IN100, Parts I and II (Met Trans A 47A:2346-2361, 2016; Met Trans A 47A:2362-2375, 2016) and on their response to his initial comments (Met Trans A 47A:3806-3809, 2016). In this recent submission, Campbell provides some very interesting thoughts on why bifilms were not observed by Kaplan and Fuchs and creates a new theory for the formation of defects referred to as bifilms. However, Campbell again provides no evidence to substantiate the presence of bifilms in Ni-base superalloys or his newly theorized mechanism. The vast majority of Campbell's comments are based solely on the re-interpretation of the photomicrographs and the data reported in the literature, including those presented by Kaplan and Fuchs (Met Trans A 47A:2346-2361, 2016; Met Trans A 47A:2362-2375, 2016). Campbell claims that bifilms are present throughout Ni-base superalloys, even though no one else has reported the presence of bifilms in Ni-base superalloys. In re-interpreting the data and images, Campbell ignores the extensive surface characterization results reported by Kaplan and Fuchs (Met Trans A 47A:2346-2361, 2016; Met Trans A 47A:2362-2375, 2016) that clearly indicate that there are no oxide films or bifilms on the fracture surfaces examined. Please note that this discussion of Campbell's most recent letter will be limited to Ni-base superalloys, since that is the subject of the research reported by Kaplan and Fuchs.

  13. Accelerated lattice Boltzmann model for colloidal suspensions rheology and interface morphology

    CERN Document Server

    Farhat, Hassan; Kondaraju, Sasidhar

    2014-01-01

    Colloids are ubiquitous in the food, medical, cosmetics, polymers, water purification, and pharmaceutical industries. The thermal, mechanical, and storage properties of colloids are highly dependent on their interface morphology and their rheological behavior. Numerical methods provide a convenient and reliable tool for the study of colloids. Accelerated Lattice Boltzmann Model for Colloidal Suspensions introduce the main building-blocks for an improved lattice Boltzmann–based numerical tool designed for the study of colloidal rheology and interface morphology. This book also covers the migrating multi-block used to simulate single component, multi-component, multiphase, and single component multiphase flows and their validation by experimental, numerical, and analytical solutions.   Among other topics discussed are the hybrid lattice Boltzmann method (LBM) for surfactant-covered droplets; biological suspensions such as blood; used in conjunction with the suppression of coalescence for investigating the...

  14. Light Asymmetric Dark Matter on the Lattice: SU(2) Technicolor with Two Fundamental Flavors

    DEFF Research Database (Denmark)

    Lewis, Randy; Pica, Claudio; Sannino, Francesco

    2012-01-01

    The SU(2) gauge theory with two massless Dirac flavors constitutes the building block of several models of Technicolor. Furthermore it has also been used as a template for the construction of a natural light asymmetric, or mixed type, dark matter candidate. We use explicit lattice simulations...

  15. Alpha-emission channeling investigations of the lattice location of Li in Ge

    NARCIS (Netherlands)

    Wahl, U; Jahn, SG; Restle, M; Ronning, C; Quintel, H; BharuthRam, K; Hofsass, H

    1996-01-01

    The alpha-emission channeling and blocking technique is a direct method for lattice site determination of radioactive atoms in single crystals. Position-sensitive detection of emitted alpha-particles provides an efficient means of carrying out such experiments at very low doses (10(10)-10(11) cm(-2)

  16. Light Asymmetric Dark Matter on the Lattice: SU(2) Technicolor with Two Fundamental Flavors

    DEFF Research Database (Denmark)

    Lewis, Randy; Pica, Claudio; Sannino, Francesco

    2012-01-01

    The SU(2) gauge theory with two massless Dirac flavors constitutes the building block of several models of Technicolor. Furthermore it has also been used as a template for the construction of a natural light asymmetric, or mixed type, dark matter candidate. We use explicit lattice simulations to ...

  17. High temperature properties of polycrystalline γ{sup '}-strengthened cobalt-base superalloys; Hochtemperatureigenschaften polykristalliner γ{sup '}-gehaerteter Kobaltbasis-Superlegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Alexander

    2016-07-01

    The recent discovery of a stable γ{sup '}-phase in Co-based superalloys opened up a pathway for the development of a new high temperature material class, which is similar in microstructure and properties to the modern γ{sup '}-hardened Ni-based superalloys. In this work, the first attempt was done to check the influence of several for Ni-based superalloys typical alloying elements on the properties of the new Co-based superalloys. It became clear that the basic characteristics of the first experimental alloys are similar to those of the γ{sup '}-hardened Ni-based alloys. The results of the multinary experimental alloys show that, based on the insight gained so far, targeted alloy development is possible. These materials have the potential to be used as disc materials in turbines.

  18. Hamiltonian monodromy as lattice defect

    OpenAIRE

    Zhilinskii, B.

    2003-01-01

    The analogy between monodromy in dynamical (Hamiltonian) systems and defects in crystal lattices is used in order to formulate some general conjectures about possible types of qualitative features of quantum systems which can be interpreted as a manifestation of classical monodromy in quantum finite particle (molecular) problems.

  19. Triangles in a Lattice Parabola.

    Science.gov (United States)

    Sastry, K. R. S.

    1991-01-01

    Discussed are properties possessed by polygons inscribed in the lattice parabola y=x, including the area of a triangle, triangles of minimum area, conditions for right triangles, triangles whose area is the cube of an integer, and implications of Pick's Theorem. Further directions to pursue are suggested. (MDH)

  20. Nucleon structure using lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Alexandrou, C.; Kallidonis, C. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus). Computational-Based Science and technology Research Center; Constantinou, M.; Hatziyiannakou, K. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Drach, V. [DESY Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC; Jansen, K. [DESY Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC; Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Koutsou, G.; Vaquero, A. [The Cyprus Institute, Nicosia (Cyprus). Computational-Based Science and technology Research Center; Leontiou, T. [Frederick Univ, Nicosia (Cyprus). General Dept.

    2013-03-15

    A review of recent nucleon structure calculations within lattice QCD is presented. The nucleon excited states, the axial charge, the isovector momentum fraction and helicity distribution are discussed, assessing the methods applied for their study, including approaches to evaluate the disconnected contributions. Results on the spin carried by the quarks in the nucleon are also presented.